A suicide bomber has killed 11 people at a mosque in the twin towns of Gamboru and Ngala in Borno state.
It was learnt that the incident happened in the early hours of Wednesday.
A senior security official said the male suicide bomber detonated an improvised explosive device (IED) after he sneaked into the mosque while worshippers were observing early morning prayers.
It is not clear how many people sustained injuries from the bombing.
The attack comes after the army imposed a temporary curfew to track down Boko Haram insurgents who are suspected to have infiltrated Maiduguri, the state capital.
On Tuesday, the insurgents were said to have killed 25 firewood sellers.
Abubakar Shekau, leader of the Boko Haram sect, appeared in a video clip where he took responsibility for series of attacks in and around the state in the past months.