More than 260 Boko Haram militants have surrendered in north-eastern Nigeria, the military has said.

The military says it has also killed a man featuring in the group’s recent propaganda videos, pretending to be its deceased leader Abubakar Sheku.

The army said it had killed Sheku last year, but never provided proof.

Boko Haram has suffered heavy losses in recent weeks as the Nigerian military battles the group close to its hometown of Maiduguri in the north-east.

The military said that 135 Boko Haram members surrendered with their weapons in Biu, Borno State, on Tuesday – and that 133 others surrendered elsewhere in north-eastern Nigeria.

It was also the first time that the Nigerian military has publicly mentioned the death of the group’s leader Abubakar Shekau, who security forces claimed had died in clashes with the army in 2009.

General Chris Olukolade of the Nigerian military said that a man named Mohammed Bashir was among those killed in the latest offensive against Boko Haram last week.

Bashir “had been acting or posing in videos as the deceased Abubakar Shekau, the eccentric character known as leader of the group”, he added.

The military however did not give any dates or locations for when they believe leader Shekau actually died.