Nigerian President Goodluck Jonathan has declared a state of emergency in three states after a series of deadly attacks by Islamist militant groups.
The military will take "all necessary action" to "put an end to the impunity of insurgents and terrorists" in Borno, Adamawa, and Yobe, he said.
Mr Jonathan also ordered more troops to be sent to the north-eastern states.
Militants from Boko Haram have been blamed for most of the violence, which has left 2,000 people dead since 2010.
The Islamist group, whose name means "Western education is forbidden" in the local Hausa language, is fighting to overthrow the government and create an Islamic state in the north.
Nigeria - a multi-ethnic nation of more than 160 million people - is also affected by a spate of conflicts over land, religion and oil.