Suspected Islamist fighters launched coordinated attacks on an army base and a military outpost in northeastern Borno State, killing at least 15 people, security sources told Reuters.
Boko Haram and Islamic State West Africa Province (ISWAP) fighters have mainly operated in the northeast of Nigeria, attacking security forces and civilians and killing and displacing tens of thousands of people.
In the latest assault, Boko Haram insurgents and ISWAP fighters attacked an army base in the Wajiroko area of Borno State at about 2100 GMT on Monday and set military equipment on fire.
One of the soldiers in the Wajiroko brigade said that at least four soldiers had been killed and several others injured, including the brigade commander.