Suspected Islamists raided the remote northeast Nigerian town of Damboa over the weekend, shooting dead more than 40 residents and burning down houses in a familiar pattern of killing that has forced tens of thousands to flee their homes this year.

Witnesses and a security source said the gunmen, thought to be members of Boko Haram, struck before dawn on Saturday.

They added that the near total lack of phone network meant no one could call for help.

Boko Haram, which is fighting for an Islamic state in Nigeria, has relentlessly targeted civilians this year, mostly in the remote, hilly region bordering northern Cameroon.

Survivor Abdul Bulama, a resident who fled Damboa to the nearby town of Biu, said 46 bodies had been recovered for burial.

A security source in Maiduguri, the main city in the northeast and birthplace of the insurgency, said more than 40 had died.

"Everybody is in fear now that Boko Haram may return for more attacks," Bulama said. "The town is deserted."

Damboa has been attacked before this year, and Bulama said life was just "getting back to normal".

A military operation in the northeast has so far failed to quell the rebellion and has triggered reprisal attacks that are increasingly targeting civilians, after they formed vigilante groups to try to help the government flush out the militants.

The sect sees all who do not believe in its austere brand of militant Sunni Islam as enemies who must be killed.

A wave of bombs across the country since April, including three in the capital Abuja and one in the commercial hub of Lagos, in the southwest, have demonstrated their ability to strike across Africa's top oil producer and biggest economy.

More than 200 school girls kidnapped by the rebels last month remain in captivity.