Islamist sect Boko Haram has terrorised northern Nigeria for years. Thousands of people have been killed in attacks — the most recent occurred on Tuesday in the city of Jos. These are the most serious attacks in recent months:
February 25, 2014: About 50 gunmen storm a school complex in northern Yobe State, killing 43 people. Many of the mostly young victims are found with their throats cut.
March 1: 52 people are killed when two car bombs explode in Borno State Capital Maidiguri. Most victims are football fans watching a game broadcast on television in a restaurant. Later that day, Boko Haram attacks the village of Mainok in Borno, killing 39 people.
March 3: Boko Haram attacks a village near Maiduguri with machine guns and rocket launchers, killing some 80 people.
March 23: At least 17 people are killed in a bomb attack on a fish market in Borno State.
March 25: A suicide bomber drives a car loaded with explosives into a police patrol vehicle in Maiduguri, killing eight people.
April 3: In north-western Zamfara State, at least 22 people are killed by gunmen attacking two villages on 50 motorbikes.
April 14: More than 200 people are killed in a bomb blast on a crowded bus terminal on the outskirts of the capital, Abuja. President Goodluck Jonathan suspects Boko Haram to be behind the attack. In the night of April 14, Boko Haram kidnaps more than 200 mostly Christian schoolgirls from their dormitory in Chibok village, in Borno.
May 6: In another kidnapping, 11 girls are abducted from the village of Waranbe, in the Gwoza local government area in Borno State.
May 19: At least 15 people are killed in a suicide attack in a predominantly Christian neighbourhood of the key northern city of Kano.
May 20: Twin blasts in a crowded market area in the central Nigerian city of Jos, in Plateau State, kill at least 118 people and seriously injure another 47.