At least 80 people were killed on Monday when Boko Haram Islamic extremists struck the northeastern Nigerian city of Maiduguri for the first time in months with rocket-propelled grenades and multiple suicide bombers, witnesses said.

The 80 people killed include 30 in Madagali, a town 150 kilometres southeast of Maiduguri, where a twin suicide bombing took place, witnesses said.

Danladi Buba said two women detonated at a market near a busy bus station at about 9 AM Brig Gen Victor Ezugwu, the officer commanding in northeast Adamawa State, confirmed the attack but said casualties have yet to be established.

At least 50 people were killed and the death toll could go higher.

In Maiduguri, capital of neighbouring Borno state, at least 30 were killed and more than 90 wounded in overnight blasts and shootouts, and another 20 died in a bombing outside a mosque at dawn on Monday, said Muhammed Kanar, area coordinator of the National Emergency Management Agency.

The military said there were multiple attacks at four southwestern entry points to the city.

In another blast, two girls blew themselves up in Buraburin neighbourhood, killing several people, according to civil servant Yunusa Abdullahi.

"We are under siege," Abdullahi said. "We don’t know how many of these bombs or these female suicide bombers were sneaked into Maiduguri last night." He said some residents have found undetonated bombs.

The attack appears to be a challenge to President Muhammadu Buhari’s declaration last week that Boko Haram has been "technically" defeated, capable of no more than suicide bombings on soft targets.

Acting on information provided by a captured insurgent, Nigerian troops "intercepted and destroyed" 13 suicide bombers and arrested one female suicide bomber in repelling the attackers, Maj Gen Lamidi Adeosun, the commander prosecuting Nigeria’s war against Boko Haram, told reporters.

Maiduguri, the city under attack, is the birthplace of Boko Haram, which emerged as a much more radical entity after Nigerian security forces launched an all-out assault on their compound in the city, killing 700 people in 2009.

Militants firing indiscriminately from the back of three trucks attacked the outlying village of Dawari, soldiers engaged them, and as people were fleeing, a woman ran into the area yelling "Boko Haram, Boko Haram." When people gathered, she detonated herself, according to village head Bulama Isa.

A rocket-propelled grenade then exploded, setting alight grass-thatched huts, and a second woman blew herself up, according to Isa. Among those killed was the village chief and 10 of his children, according to residents Ahmed Bala and Umar Ibrahim.