In January, a coordinated assault on government buildings and other sites in Kano by Boko Haram killed at least 185 people. In the time since, the sect has been blamed for attacking police stations and carrying out smaller assaults in the city.
On Thursday, the sect carried out a suicide car bombing at the Abuja offices of the influential newspaper ThisDay and a bombing at an office building it shared with other publications in the city of Kaduna. At least seven people were killed in those attacks. Late Thursday night, gunmen also bombed a building at the campus of Gombe State University, though authorities said no one was injured in the attack.
Boko Haram has rejected efforts to begin indirect peace talks with Nigeria's government. Its demands include the introduction of strict Islamic law across the country, even in its predominantly Christian south, and the release of all imprisoned followers.
Churches also have been increasingly targeted by Boko Haram. A Christmas Day suicide bombing of a Catholic church in Madalla near Nigeria's capital killed at least 44 people.
Nigeria, a multiethnic nation of more than 160 million people, has seen anger grow over crushing poverty and corrupt politicians in the north, fueling resentment against the government and the West in the oil-rich nation.
Associated Press writer Haruna Umar in Maiduguri, Nigeria contributed to this report.
Jon Gambrell reported from Lagos, Nigeria, and can be reached at http://www.twitter.com/jongambrellap.