Nigeria's militant Islamist leader Abubakar Shekau may have been killed by the security forces during a shoot-out, an army spokesman has said, according to BBC News.

An "intelligence report" showed that Shekau, the leader of the Boko Haram group, may have died between 25 July and 3 August, Lt-Col Sagir Musa said.

Boko Haram, which has waged an insurgency in Nigeria since 2009, has not commented on the statement.

The U.S. had put a bounty of $7m (£4.6m) on Shekau's head.