Militant group Boko Haram has been blamed for scores of shootings and bombings in the north, including a spate of attacks in the past few weeks.

Nigeria's Army killed more than 50 members of the group during fighting on Thursday and Friday in the northeastern city of Damaturu, the force's chief of staff Lt. Gen. Azubuike Ihejirika said in comments published in local media.

Three soldiers also died, he added.

"There was a major encounter with Boko Haram in Damaturu and we overran their stronghold and their ammunition site," Ihejirika said.

"They came with sophisticated and heavy weaponry including GPMGs (machine guns) and bombs but our trained soldiers subdued them."

Hospital sources in Damaturu said they had counted 50 bodies so far, but most of the dead were civilians.

"So far 50 bodies have been deposited at the mortuary by the military and police operatives," a hospital worker told Reuters by telephone. "They were ... seven policemen, two soldiers and 41 civilians."

In a separate incident in Damaturu on Friday, suspected Boko Haram members opened fire on a group of policemen shortly after prayers, killing four, police officials said.

At least 11 people were killed in another shootout in the northeastern city of Maiduguri, Boko Haram's heartland, on Thursday, a morgue official said.

Clashes between security forces and the group, whose name roughly translates as "Western education is forbidden," have become increasingly frequent in the past couple of weeks, as the north's simmering conflict escalates.

There was no immediate comment from Boko Haram, which rarely makes public statements.

Before this year, the insurgency was largely contained in its heartland in the remote northeastern city of Maiduguri. Since then it has spread to other parts of the north, including neighboring Yobe state, where Damaturu lies.

Damaturu was the scene of the most deadly Boko Haram assault to date when 65 people were killed in a wave of shootings and bombings on Nov. 5 that left churches, police stations and mosques reduced to smoldering rubble.

This year the group struck the capital Abuja twice, including a suicide car bomb attack against the UN headquarters that killed 26 people.