At least 50 people have been killed in a suicide bombing on a mosque in northeast Nigeria, according to police.

Police say the young bomber was mingling with worshippers in the town of Mubi when he detonated his explosives.

Police spokesman Abubakar Othman said the number of dead could rise further "as those seriously injured could add to the figure".

Mubi is in Adamawa state, where Boko Haram held territory until the Islamist militants were pushed back by troops in early 2015.

The explosion bore the hallmarks of a Boko Haram attack. The extremists often strike with suicide bombings in crowded public places like mosques and markets.

The latest attack is the highest loss of life since 56 people were killed in the same state last December, when two schoolgirl suicide bombers killed 56 people and wounded dozens more in a crowded market.

Boko Haram has waged an insurgency in northeast Nigeria since 2009 - killing more than 20,000 and forcing some two million to flee their homes in an attempt to create an Islamic State.

Most attacks by the group focus on Borno state, the birthplace of the insurgency.

The group held a swathe of land around the size of Belgium in Borno, Adamawa and Yobe states until early 2015 but were forced out by Nigeria's army backed by troops from neighbouring countries.