The Nigerian military says it has repelled coordinated insurgent attacks in the northeastern Borno state, killing 40 suspected militants.
In a statement Tuesday, authorities said the attacks occurred recently in the towns of Bama, Gwoza and Pulka.
It says the unrest involved fighters "of unknown strength."
Northern Nigeria has been a stronghold for Boko Haram, a militant group that has been fighting to impose a strict form of Islamic law on the Muslim-majority region.
Boko Haram has been blamed for thousands of deaths since it launched an insurgency against the government in 2009.