At least 28 people were killed in a suicide bombing at a mosque in Maiduguri, northeast Nigeria, on Friday, raising fresh security concerns after a wave of similar attacks.

At least 28 people were killed in a suicide bombing at a mosque in Maiduguri, northeast Nigeria, on Friday, raising fresh security concerns after a wave of similar attacks.

The attack happened shortly after 5:00 am (0400 GMT) in the Jidari area of the Borno state capital, which has previously been targeted by Boko Haram militants.

Maiduguri has now been hit six times this month, killing a total of 76 people, according to an AFP tally, underscoring an increased risk to civilians after similar strikes in neighbouring states and near the capital, Abuja.

Umar Sani, a civilian vigilante assisting the military in the counter-insurgency, and local resident Musa Sheriff both told AFP there were two blasts at the mosque.

"People from various mosques nearby rushed to the scene to assist the victims," said Sani.

"I was involved in the evacuation. We counted 28 dead bodies apart from the two bombers, who were identifiable by the mutilation of their bodies.

"Over 20 other people were injured."

Sheriff, who said he escaped with his life as he was late for prayers, gave a similar account.

Both men also said two other people were arrested and handed over to the military for questioning after they were seen apparently celebrating following the blasts.

The two men were "standing from afar, hugging each other like a celebration, chanting "Allahu Akbar" (God is greatest)", said Sani.

"The rescuers apprehended them. They used ropes to tie them and they confirmed that two of their comrades carried out the attacks. They were unrepentant," he added.

"To them it was a mission accomplished," said Sheriff.