Nigeria has seen a recent upsurge in violence linked to the Islamist extremist group Boko Haram, with the insurgency having left more than 13,000 dead since 2009. Here is a list of recent incidents:
April 14: 276 young girls are seized from their school by Boko Haram gunmen in Chibok, a remote corner of Borno state in northeastern Nigeria. Fifty-seven of the girls manage to flee, while 219 are still being held.
April 14: At least 75 people die in a bomb blast in a packed bus station on the outskirts of Nigeria's capital Abuja -- the deadliest attack yet to strike the city. Boko Haram claims responsibility.
May 5: Boko Haram gunmen raze the town of Gamboru Ngala in Borno state, killing at least 300 people, according to local sources.
May 20: Twin car bombings in the central Nigerian city of Jos, blamed on Boko Haram, kill at least 118 and bring entire buildings down.
June 1: A bomb attack targeting fans at a football match in the town of Mubi, in northeastern Adamawa state, kills more than 40.
June 3: Heavily armed gunmen raid four northeastern villages in Borno state, with local leaders putting the death toll as high as 400-500. A day later another attack kills 45 on the outskirts of Maiduguri, the capital of Borno state.
June 29: More than 50 are killed when suspected Boko Haram gunmen riding on motorcycles target churches in four villages near Chibok during Sunday services.
July 23: Two blasts rock northern Kaduna city killing at least 42. A local official says former military ruler turned opposition figurehead Muhammadu Buhari was the target of the second attack but was unhurt.
August 24: Boko Haram leader Abubakar Shekau claims he has created an Islamic caliphate in the town of Gwoza, in Borno state.
October 18: Around 60 women and young girls are abducted around Chibok, according to witnesses.
October 26: A local chief says 30 adolescents have been abducted in the village of Mafa in Borno state.
October 31: Shekau says the 219 abducted schoolgirls have been converted to Islam and married off, ruling out talks with the authorities on a ceasefire.
November 9: Shekau says that he has created a caliphate in the more than 20 northeastern towns conquered by the insurgents.
November 10: A suicide attack kills at least 58 people at a boys school in Potiskum in Yobe state.
November 19: At least 45 are killed in an attack blamed on Boko Haram on a village in the Mafa region.
November 20: 48 fishmongers have their throats cut or are drowned by the group at Doron Baga, on the shores of Lake Chad.
November 25: More than 45 people die in twin bomb blasts at a packed market in Maiduguri.
November 28: Two suicide bombers blow themselves up and gunmen open fire during weekly prayers at the mosque of the Emir of Kano, one of Nigeria's top Islamic leaders. At least 120 people are killed and 270 others wounded.
Police officers stand near wreckage at a scene of multiple bombings at Kano Central Mosque. (Reuters)