Human rights organizations estimate some 3,000 Nigerians have been killed in violence related to militant Islamist group Boko Haram over the past three years. Numerous negotiation attempts have stalled due to distrust on both sides, and the factionalized leadership of the group's different cells.
Below is a chronology of violence relating to Boko Haram and the government's police and military crackdown since January 2012. See here for an earlier IRIN timeline covering 2002 to January 2012.
21 February 2013: Nigerian government begins official search for a French family taken hostage on 19 February in Cameroon near the Nigerian border. Suicide blast targeting a military patrol vehicle in Maiduguri kills a civilian and injures six soldiers. A section of a market and adjoining shops, as well as a petrol station, are burnt.
20 February 2013: Two civilians and a suspected bomber are killed in a blast targeting a military patrol vehicle in Maiduguri.
19 February 2013: French President François Hollande accuses Boko Haram (BH) of the abduction of a French family in Cameroon on the border with Nigeria's Borno State.
18 February 2013: Ansaru, in an email statement, claims the kidnap of seven expatriate construction workers in Bauchi State.
17 February 2013: Construction firm evacuates staff from Jama'are in Bauchi State.
16 February 2013: Gunmen kidnap seven foreign construction workers - a Briton, an Italian, a Greek and four Lebanese - in Jama'are, killing a security employee.
15 February 2013: Two suicide bombers are killed in an attack targeting a military patrol vehicle in Maiduguri in which at least one soldier is injured. Several homes, shops and vehicles are burnt in the explosion.
11 February 2013: Police in Kano parade seven BH members suspected of involvement in the 19 January 2013 attack on the convoy of the emir of Kano which killed five people. Eight other BH members are declared wanted.
10 February 2013: Three North Korean doctors are killed by unknown attackers in Potiskum in northeastern Yobe State.
8 February 2013: Gunmen kill 10 polio immunization workers and injure three others in separate attacks on two polio clinics in Kano.
1 February 2013: Nigerian troops kill 17 Islamists in raids on BH training camps in two forests outside Maiduguri.
28 January 2013: A purported BH commander declares a ceasefire on behalf of the sect.
27 January 2013: Assailants kill eight residents of Gajiganna village near Maiduguri.
23 January 2013: Assailants behead five residents in the Gwange area of Maiduguri.
22 January 2013: Gunmen kill five men playing draughts and injure two others in the Dakata District of Kano.
21 January 2013: Some 18 local hunters are killed by gunmen in an attack on a market in Damboa town in Borno State.
19 January 2013: Two Nigerian soldiers are killed and five others seriously injured in a bomb attack on a contingent of Mali-bound Nigerian troops in central Kogi State. BH splinter group Ansaru claims responsibility. Five people are killed in an attack on the convoy of the emir of Kano Ado Bayero in Kano.
18 January 2013: Nigerian authorities announce the arrest of two masterminds of a 25 November 2012 twin-car bomb attack on a church in Jaji military cantonment near Kaduna.
17 January 2013: Nigeria begins troop deployment to Mali to help fight Al Qaeda-linked Islamists, some of whom it has accused of providing support to BH. Four people, including two BH gunmen, are killed in a shootout with soldiers at a military checkpoint in Kano. Five gunmen are arrested.
13 January 2013: A key BH commander is arrested in Maiduguri.
4 January 2013: Five BH gunmen, a soldier and a policeman are killed in an attack by Islamists on a military checkpoint in Marte town near the border with Cameroon.
2 January 2013: BH attacks a police station, kills two policemen and two civilians in Song town of Adamawa State.
1 January 2013: Thirteen gunmen and a soldier are killed in a shootout in Maiduguri.
30 December 2012: A policeman and a civilian are killed in a blast at a police station in Bunkure town outside Kano. The police station is burnt in the attack.
29 December 2012: Four BH gunmen and a policeman killed in a security raid on a sect hideout in Potiskum, Yobe State.
28 December 2012: Assailants kill 15 Christians in Musari area on the outskirts of Maiduguri. Five residents and two policemen killed in bomb and gun attacks on government buildings in Maiha town in Adamawa State.
27 December 2012: Five BH Islamists killed in a military raid on a sect hideout in Rigasa area of Kaduna where arms are recovered.
24 December 2012: Six Christians, including a priest, killed in a church attack in Piri village outside Potiskum.
23 December 2012: Ansaru claims responsibility for the kidnap of a French national in Rimi village outside Katsina, cliting France's planned intervention in northern Mali.
22 December 2012: Two suicide bombers attack two mobile telecom companies in Kano.
19 December 2012: Islamists kidnap a French national in Rimi village outside Katsina.
9 December 2012: Three Islamists and a police officer killed in an attack on a regional police formation in Potiskum.
1 December 2012: Assailants kill 10 Christian residents in Chibok town outside Maiduguri. Two policemen killed in BH attacks on security border posts in Gamboru Ngala on the border with Cameroon.
27 November 2012: Troops kill three Islamists and arrest 31 others in a raid on a sect hideout in Maiduguri. A soldier is killed and another injured in the raid.
25 November 2012: Two policemen killed and 30 detained Islamists freed in an attack by Ansaru gunmen on the Special Anti-Robbery Squad (SARS) headquarters in Abuja. Eleven killed and dozens injured in a twin-car bomb attack on a church in Jaji military cantonment outside Kaduna. A Christian couple and their child are killed by BH gunmen in Kano.
23 November 2012: Nigerian military declares 19 BH leaders wanted and offers reward for information leading to their capture.
21 November 2012: Islamists enter three homes of security personnel in Maiduguri and kill five children.
15 November 2012: Soldiers kill a top BH commander accused of killing ex-General and Nigerian civil war hero Mamman Shuwa in Maiduguri.
10 November 2012: Gunmen kill five Christians in Gaidam town in Yobe State.
9 November 2012: Three policemen killed and three churches burned in coordinated attacks in Bonny Yadi town, Yobe State.
7 November 2012: BH gunmen kill two Chinese construction engineers in an attack on a Chinese construction company yard in Benishek town outside Maiduguri.
6 November 2012: Four Islamists killed and four others arrested in a military raid on a sect hideout in Fika town, Yobe State.
4 November 2012: Three killed in drive-by shooting by BH Islamists in the Kawo area of Kano.
2 November 2012: BH gunmen kill ex-General and Nigerian civil war hero Mamma Shuwa in his home in Maiduguri. A firefighter and two security guards are killed by Islamists while trying to put out a fire (started by Islamists) in a local government secretariat building in Damboa town outside Maiduguri.
1 November 2012: A purported BH commander makes conditional talks offer to the Nigerian government.
28 October 2012: Ten killed and 145 injured in a suicide bomb attack on a church in Kaduna and reprisal attacks by Christians on Muslim residents.
21 October 2012: Six soldiers killed in a bomb attack targeting a military patrol vehicle in Potiskum.
20 October 2012: Gunmen kill eight residents of Potiskum in targeted killings.
19 October 2012: Troops arrest a high-profile BH member in the home of a Nigerian senator in Maiduguri. A Chinese construction worker is killed at a construction site in Maiduguri.
18 October 2012: Twenty-three killed in coordinated bomb and gun attacks by BH in Potiskum. Several government buildings and schools are burnt in the attacks.
15 October 2012: Troops kill 24 BH Islamists in shootout in Maiduguri.
14 October 2012: A Christian couple and their child are gunned down as they leave a church in the Gwange area of Maiduguri. A local chief in the area is also killed in his house.
11 October 2012: Human Rights Watch puts the death toll of those killed in BH violence at 2,800 since 2009, saying Nigerian security forces as well as BH may both be guilty of crimes against humanity.
2 October 2012: Gunmen suspected to be BH Islamists shoot and slit the throats of 26 people in a student housing area in Mubi town in Adamawa State on the border with Cameroon.
30 September 2012: A bomb blast and gunfire shake an area around an Islamic boarding school in the city of Zaria, leaving two BH Islamists dead and three others wounded.
29 September 2012: Nigerian military announces the arrest of an immigration officer in Yobe State over link with BH.
25 September 2012: Troops kill a senior BH Islamist leader and arrest 156 suspected sect members during a weekend raid in Mubi town in Adamawa State.
24 September 2012: Soldiers kill 35 BH Islamists in a crackdown on the insurgent group in the northeastern city of Damaturu.
23 September 2012: A suicide bomber blows up his explosives-laden car near a church in the city of Bauchi, killing a female worshipper and her son and injuring dozens. Authorities announce a round-the-clock curfew in Damaturu and Potiskum in a bid to hunt down BH members.
20 September 2012: Soldiers in Maiduguri kill two senior BH commanders in a shootout. Eight suspected Islamists are also arrested in a separate incident.
17 September 2012: Nigerian soldiers shoot dead BH spokesman on the outskirts of Kano. Gunmen kill Borno State justice commissioner in his hometown of Bama and also an ex-Nigerian prisons chief in Azare town in Bauchi State.
16 September 2012: Six are shot dead and nine injured when BH gunmen fire into a group of ludo game players in Bauchi. Islamists kill a Nigerian security officer and three members of his family in Kano.
12 September 2012: Troops arrest 11 Islamists and recover arms and explosives in a raid near Maiduguri.
7 September 2012: Soldiers gun down seven Islamists in a shootout in Maiduguri.
4-5 September 2012: BH launches attacks on at least two dozen mobile phone towers across northern Nigeria in which more than 20 people are killed.
26 August 2012: Gunmen open fire and kill a policeman as he walks home from work in Damaturu.
19 August 2012: Gunmen blow up a primary school, a church and police station in Damagun town in Yobe State. Two gunmen on motorcycles open fire on troops at a military checkpoint in Kano, injuring a soldier.
12 August 2012: A military raid on a BH hideout in Maiduguri leaves 20 Islamists and a soldier dead. Two Islamists are killed and more than 30 others arrested by a joint military and police team in a shootout in Damaturu.
6 August 2012: BH gunmen open fire on an evangelical church during a service in Okene in Kogi State, central Nigeria, killing at least 19 people. Two soldiers are shot dead by gunmen who fire on their patrol van in the same city.
3 August 2012: A top Muslim traditional leader in Potiskum escapes a suicide attack when the bomber is thwarted by locals before blowing himself up outside a mosque.
1 August 2012: Two BH Islamists are killed by soldiers during a shootout on the border with Chad while trying to smuggle heavy weapons into the country.
30 July 2012: Suicide bombings at two police stations kill two people in the city of Sokoto, the historic seat of Islam in Nigeria.
29 July 2012: A gun battle near a mosque in Kano and two other shootings leave at least eight dead, including two air force personnel and three BH gunmen. Two former Nigerian leaders issue a rare joint statement calling for talks to end BH violence, warning the violence could put the nation's unity at risk.
28 July 2012: Nigerian soldiers arrest 26 BH members and kill two others in a raid in Maiduguri after an attack leaves two Indian nationals dead.
25 July 2012: Gunmen attack a factory in Maiduguri, killing two Indian nationals and stealing US$600.
22 July 2012: A bomb blast in Bauchi city, in an area with clusters of bars and entertainment spots, kills a 10-year-old boy and wounds 10 others.
19 July 2012: Gunmen on two motorcycles kill three people, including a police constable, in Kano. Two traders are shot dead by gunmen in a major market in Maiduguri.
18 July 2012: Nigeria lifts a six-month state of emergency it imposed in four states following a wave of BH attacks.
16 July 2012: Police repel a BH attack on police headquarters in Damaturu.
13 July 2012: Five people are killed in a failed suicide attack on Shehu of Borno, an influential Islamic and traditional leader, outside a mosque in Maiduguri.
10 July 2012: BH claims responsibility for raids by gunmen in central Plateau State on 7-8 July which leave more than 100 people dead.
5 July 2012: A Nigerian court accuses two men of having links with Al-Qaeda in the Arabian Peninsula and of receiving funds from the militant group to be used in conscripting and sending recruits to Yemen.
3 July 2012: Explosion outside a shopping mall in Abuja; a second unexploded bomb is later discovered.
2 July 2012: Attackers kill nine construction workers in their lodge in Maiduguri.
30 June 2012: Security forces kill three in a pre-emptive offensive against BH Islamists in Damaturu.
26 June 2012: Police in Kano repel coordinated BH attacks on police formations in which a police officer is killed; 17 Islamists killed and three arrested. Gunmen launch an overnight attack on a regional police headquarters in the town of Wukari in Taraba State, killing three officers. Two civilians are also killed in the attack.
24 June 2012: BH Islamists raid a prison in Damaturu, leaving four prison guards dead and freeing 40 Islamists.
22 June 2012: Nigerian President Goodluck Jonathan fires his national security adviser and defence minister. A blast goes off outside a nightclub in Abuja - no casualties.
21 June 2012: The USA designates three leaders of BH as "global terrorists". Nigerian troops arrest a high-profile BH member suspected of involvement in the suicide bombing of a UN building in Abuja that killed 26, and Christmas Day bombings near Abuja that killed at least 44 people outside Abuja.
19 June 2012: Gun battles between security forces and BH gunmen in Damaturu kill 34, including three police officers and a soldier.
17 June 2012: BH claims suicide attacks at three churches in Kaduna and Zaria, sparking reprisal violence by Christian mobs who burn mosques and target their Muslim neighbours. More than 100 are killed over a week.
15 June 2012: Nigerian troops kill four suspected BH Islamists during a dawn raid on a sect hideout in Kano.
12 June 2012: Gunmen kill a lawyer in Potiskum.
10 June 2012: A suicide bomber blows his car up outside a church and gunmen open fire on another church service in Jos, killing three people and wounding dozens in attacks claimed by BH. Gunman opens fire on a church in the northeastern Nigerian town of Biu, killing one person and wounding several others.
9 June 2012: Gunmen kill five people, including two policemen and a customs officer, in separate attacks in Kano and Potiskum.
8 June 2012: A suicide blast at the police headquarters in Maiduguri kills one police officer and four civilians as well as injuring several others. An improvised explosive device concealed in a bag kept under a public shed explodes and kills one in Maiduguri town.
6 June 2012: Soldiers kill 16 Islamists during a raid on a sect hideout in Maiduguri.
5 June 2012: BH gunmen kill a former deputy police chief, his driver and a bodyguard in the city of Kano. BH claims the attack.
3 June 2012: Suicide bomber tries to drive an explosives-packed car into a northern Nigeria church previously attacked by BH, killing at least 15 and injuring 40. BH claims the attack.
31 May 2012: A German hostage is killed in Kano during a rescue bid. His five captors also die in the military raid. Gunmen abduct an Italian engineer in central Kwara State.
30 May 2012: Gunmen kill two bakers and wound three others in a bakery in Maiduguri.
29 May 2012: Nigerian troops arrest a high-profile BH member on a wanted list during a raid in Kano.
28 May 2012: Gunmen on a motorcycle kill four Christian Igbo traders in Yola.
27 May 2012: Gunmen open fire on Muslim worshippers outside the home of a Shiite Muslim cleric in Potiskum, killing three people.
26 May 2012: Gunmen kill a Muslim cleric and a retired prison guard in separate attacks in Potiskum.
23 May 2012: A police officer and a civilian are killed in a gunfight between police and Islamists outside a police station in Sokoto.
21 May 2012: Kano police arrest a person suspected of involvement in BH attacks on church services in which 20 people are killed.
17 May 2012: Militants bomb two empty schools in Kano. No casualties.
13 May 2012: Gunmen open fire on card players in Kano, killing three, including a prison warden.
11 May 2012: Nigerian troops arrest a leading BH militant, his wife and five children in a raid in Kano.
12 May 2012: Gunmen burn down a police station in Mafa town outside Maiduguri, killing two policemen and a civilian.
9 May 2012: Soldiers in Maiduguri kill a BH Islamist and wound two others while repelling an attack.
6 May 2012: Soldiers in Kano kill four members of BH and arrest 12 others in a raid on a sect hideout.
5 May 2012: Gunmen open fire on a wedding party in Maiduguri, killing three people and injuring four others, including two soldiers.
4 May 2012: Gunmen kill seven people, including two jail guards in separate attacks, and free all inmates from a local jail in Kumshe town outside Maiduguri. Police arrest 23 sect members in a foiled attack on a police station.
3 May 2012: Gunmen armed with explosives kill at least 34 people in an attack on a cattle market in Potiskum and burn it to the ground.
2 May 2012: The head of Nigeria's Christian community issues a warning to the government to bring to an end BH attacks on Christians. Police announce the arrest of an explosives' supplier to BH in Kano. Gunmen shoot dead three people in Potiskum.
1 May 2012: Nigerian troops kill a BH militant during a pre-dawn raid in Kano following weekend attacks against church services that leave around 20 people dead.
30 April 2012: A suicide attack targeting a senior police official's convoy in Jalingo (Taraba State capital) kills 11 and wounds 20; the senior officer is unharmed.
29 April 2012: About 20 are killed in bomb and gun attacks on church services at a university in Kano.
27 April 2012: Gunmen suspected of belonging to BH kill a police inspector outside his home in Damaturu.
26 April 2012: Suicide attacks against two offices (in Abuja and Kaduna) of one of Nigeria's most influential newspapers kill at least nine people, with BH claiming the attacks.
23 April 2012: Five BH militants are killed when bombs they are assembling explode during a shootout with government troops in Maiduguri.
20 April 2012: BH gunmen kill eight, including a policeman, in three separate attacks in Maiduguri.
17 April 2012: Nigerian troops kill one member of BH and arrest 13 others in dawn raids on two hideouts in Maiduguri.
13 April 2012: Gunmen shoot dead two men near a community centre showing soccer matches in northern Nigeria, days after BH reportedly called for such places to be closed.
12 April 2012: The leader of BH vows to fight on in a video message to President Goodluck Jonathan posted on YouTube.
10 April 2012: At least 10 are killed when gunmen burn down immigration and customs posts in the town of Banki on the border with Cameroon.
8 April 2012: An Easter bomb attack on a church in the northern city of Kaduna claims at least 41 lives. Several people are injured in a separate attack on a church in Jos.
5 April 2012: Seven people killed in an attack on a Maiduguri market.
2 April 2012: Gunmen shoot dead a Nigeria secret police officer at a barber's shop in the northeastern city of Maiduguri.
1 April 2012: Nigerian troops clash with members of BH while raiding a hideout, leaving 11 dead, including a soldier and policeman.
30 March 2012: Four killed when attackers use bombs and gunfire to attack a police station and rob a bank in Askira Uba town outside Maiduguri.
29 March 2012: Gunmen bomb a police station in Damagun town outside Damaturu and free more than a dozen prisoners, leaving three assailants and a policeman killed in an attack claimed by BH.
25 March 2012: Six people - a former police officer and two of his friends as well as three gunmen - are killed in a shootout in Maiduguri.
21 March 2012: A BH spokesman rules out discussion with the government after indirect contacts. Nigerian troops ambush and kill nine gunmen after attacks on a police station and a bank in Tudun Wada town outside Kano. A BH spokesman rules out further talks with Nigeria's government after preliminary, indirect contacts.
17 March 2012: A respected cleric mediating in peace talks between the Nigerian government and BH pulls out of the negotiations, accusing the government of insincerity.
13 March 2012: Gunmen open fire and throw explosives at a military and police patrol in northeastern Nigeria, killing a policeman, a soldier and three civilians.
11 March 2012: At least 10 people are killed in a suicide attack on a church in the central city of Jos.
10 March 2012: Gunmen shoot dead a senior police officer in charge of a special squad to fight robbery in northern Nigeria's Adamawa State.
8 March 2012: A British and an Italian hostage kidnapped in Nigeria in 2011 die in a foiled rescue bid in Sokoto. The alleged mastermind of the kidnapping of a Briton and an Italian dies after suffering gunshot wounds in a security raid. Gunmen kill three policemen in an attack on a police station and two banks in Ashaka town in Gombe State.
6 March 2012: BH gunmen kill Nigeria customs chief in charge of Yobe and Borno states in his home in Potiskum. Islamists attack a prison, police station and local government office in Konduga town in northeastern Nigeria, wounding three police officers.
5 March 2012: Troops in the city of Maiduguri shoot dead three BH members as they try to burn down a public primary school. Gunmen attack the home of a senior officer in Kano, killing two officers on guard.
4 March 2012: A mob lights fires and marches through Kano to protest the killing of a motorcyclist by soldiers deployed to counter BH Islamists.
3 March 2012: Three BH Islamists are killed while assembling bombs in the city of Maiduguri.
2 March 2012: Two motorcycle-riding gunmen kill a soldier guarding the home of a senior military officer in Kano and steal his gun.
28 February 2012: Gunmen use explosives to burn a state-run primary school in Maiduguri, the fourth such attack in a week. Gunmen kill three policemen in a gun and explosives attack on a police station in the town of Jama'are in Bauchi State.
26 February 2012: Gunmen kill three policemen and wound two others in an attack on a police station in Shuwa village, Adamawa State. A suicide bomb attack kills three people outside a church in the central city of Jos.
24 February 2012: BH gunmen kill 14 people in an overnight raid on a police station in the northeastern city of Gombe.
23 February 2012: Military chief says BH tied to Al-Qaeda - the first such claim by the Nigerian government. BH gunmen kill four policemen near police chief's home in Kano and shoot dead two more in Lapai town in central Niger state.
22 February 2012: BH Islamists hurl explosives and fire at a military checkpoint, igniting a gun battle Kano. No casualties.
20 February 2012: At least 30 killed in gun and explosives attacks on a market in Maiduguri. BH claims responsibility.
19 February 2012: Several wounded in explosion near a church outside Abuja.
17 February 2012: Gunmen kill three policemen and injure another in two separate attacks in central Nigeria's Niger State capital Minna.
15 February 2012: BH launches a raid on a prison in central Nigeria in which 119 inmates are set free.
14 February 2012: A police bomb disposal expert is killed when a bomb he is defusing explodes. The bomb was planted near a military checkpoint.
12 February 2012: Army kills 12 suspected BH Islamists during a raid in Maiduguri.
10 February 2012: Two explosions outside a customs building in Maiduguri kill four BH bombers and wound two soldiers. Gunmen shoot dead two Christian traders and a Muslim cleric in separate attacks in Potiskum. Nigerian authorities re-arrest the alleged mastermind of a Christmas Day church bombing (that killed at least 44 people) after he escaped from custody.
9 February 2012: Gunmen in Kano shoot dead a man known for publicly criticizing BH Islamists.
7 February 2012: Explosions rock an army barracks, a bridge and an air base in Kaduna in suicide attacks claimed by BH.
6 February 2012: Multiple blasts at Gamboru market in Maiduguri set several vehicles and shops on fire. Gunmen blow up a police station and injure one officer in the Sharada area of Kano.
5 February 2012: Gunmen kill a secret police officer in front of his house in Damaturu.
2 February 2012: Six BH members are killed by fellow sect members in an area of Maiduguri in an internal feud. Multiple blasts rock the city.
1 February 2012: BH asks Kano residents to bear with the violence, in a bid to show people that the sect is only trying to target the government.
30 January 2012: Gunmen on motorcycles kill two people and injure two others in the town of Gamboru Ngala on the border with Cameroon. Gunmen attack two more police stations in Kano, killing at least two people. Gunmen on a bicycle shoot dead a guard outside a church in Potiskum.
29 January 2012: The Nigerian secret service says it has arrested BH spokesman Abul Qaqa at a hideout in Kaduna but BH rejects the claim, saying the man arrested is Abu Dardaa, the group's head of "Propagation and Enlightenment". In the Rigasa area of Kaduna, gunmen on motorcycles kill two policemen.
28 January 2012: A BH spokesman rejects a call by President Jonathan for talks, and threatens fresh attacks if captured BH members are not freed. Troops kill 11 BH fighters during a shootout in Maiduguri.
27 January 2012: Gunmen open fire on a police station in Kano, killing one officer.
26 January 2012: A German construction engineer is kidnapped from a construction site in Kano. An explosion rocks a bus terminal in Kano, injuring two people and forcing the area to be evacuated. The authorities announce the arrest of around 200 people following bombings and shootings in Kano, with most of those detained Chadian mercenaries.
25 January 2012: President fires the country's police chief and all six of his deputies following a wave of BH attacks.
24 January 2012: Gunmen throw explosives at, and open fire on, a police station in Kano following deadly BH attacks on 20 January.
23 January 2012: Hundreds of Muslim faithful offer special prayers for peace at Kano central mosque with the emir and the governor of Kano in attendance.
22 January 2012: President visits Kano following BH attacks on the city.
20 January 2012: At least 185 killed in Kano city following coordinated bombings and gun battles, claimed by BH.
[ This report does not necessarily reflect the views of the United Nations. ]