At least 18 people were killed and 30 others injured after a series of attacks by suspected female suicide bombers in Nigeria's northeastern Borno state on Saturday, the head of the local state emergency management agency said.

Borno is at the centre of a 15-year Islamist insurgency that has killed thousands of people and displaced millions more. Although the Nigerian military has degraded the capabilities of the militants, they still carry out deadly attacks against civilians and security targets.

Barkindo Saidu, director general of the Borno State Emergency Management Agency, said suspected suicide bombers separately attacked a wedding, funeral and hospital, killing and injuring several people in the town of Gwoza.

Saidu said 18 deaths had been confirmed, a toll that included children, adults and pregnant women.

"The degree of injuries ranges from abdominal ruptures, skull fractures, and limb fractures," he said.

No one has claimed responsibility for the attacks.

Borno state police were not immediately available for comment.

Boko Haram and its splinter group, Islamic State West Africa Province (ISWAP), are the most active militant groups in Borno, a large swathe of rural hinterland the size of Ireland.