A series of bomb blasts and gun battles have killed at least 60 people in the northeastern Nigerian town of Damaturu, sources tell Al Jazeera.
Al Jazeera's Yvonne Ndege, reporting from Abuja, said that witnesses reported scenes of "carnage" and "chaos" after several bombs and running gun battles surged on the streets of the town late on Friday and overnight.
"Eyewitnesses say that there is carnage and chaos on the streets ... they also say that they have seen up to 60 bodies in a mortuary," she said.
The Red Cross said the death toll stood at 63. But an official of the country's road safety agency who took part in the collection of bodies, told the AFP news agency that 150 people had been killed.
An AFP reporter counted 97 bodies in a hospital mortuary in northeastern Nigeria on Saturday. The remaining bodies had reportedly been already collected for burial.
"It is diffcult to verify these reports especially since this is a very remote part of the country," Ndege said.
The violence follows a series of attacks reported in the neighbouring cities of Maiduguri and Potiskum on Friday afternoon.
Boko Haram responsible
The Nigerian group Boko Haram claimed responsibility for the attacks, which represent the most co-ordinated and wide-ranging assault yet in their increasingly bloody sectarian fight with the country's weak central government.
"We are responsible for the attack in Borno [state] and Damaturu," Boko Haram spokesman Abul Qaqa told the AFP on Saturday.
The Daily Trust, the newspaper of record in Nigeria's Muslim north, spoke to Abul Qaqa who said the group planned to launch new assaults.
"We will continue attacking federal government formations until security forces stop their excesses on our members and vulnerable civilians," he told the paper.
"We will continue attacking federal government formations until security forces stop their excesses on our members and vulnerable civilians"
- Abul Qaqa, spokesman of Boko Haram
Boko Haram, which means "Western education is sacrilege", has carried out a succession of recent attacks in the country, killing more than 240 people this year alone, according to AP figures.
The group wants the strict implementation of Islamic law across the nation of more than 160 million people.
Nii Akuetteh, a former executive director of Africa Action, a Washington-based rights group, said Boko Haram appeared to be growing strong.
"The government has been saying that it will deal with them and that it will get a handle on the problem, but it's not been able to," he told Al Jazeera.
"Previously, the attempt made was to try and fight them militarily - to send the secuirty forces after them - but that has created its own problem.
"I know for a fact that there're Nigerian groups in and outside the government, including the media, who are suggesting that the government should try to talk to Boko Haram, but my own impression is that they don't seem to be particularly ready or inclined to talk."
Split into factions
The Associated Press, quoting a diplomat, said the government was facing an increasingly dangerous threat from Boko Haram, adding that the group had split into three factions, one allied with al-Qaeda's north Africa branch.
It said one faction remains moderate and welcomes an end to the violence while another wants a peace agreement with rewards similar to those offered to MEND, which has been fighting for a greater share of Nigeria's oil wealth.
The series of attacks in Maiduguri on Friday began when three roadside bombs exploded in quick succession in an apparent co-ordinated strike, hitting the wards of Maiduguri and Jajeri and the El-Kanemi College of Islamic Theology.
The attacks, all of them occuring around the time of Friday prayers, caused panic in the city's mosques.
A short time later, suicide bombers driving a black SUV attempted to enter a base of the military unit charged with protecting the city from Boko Haram fighters, Hassan Ifijeh Mohammed, an army spokesman, told the AP news agency.
The SUV could not enter the gate and those inside the vehicle detonated explosives outside the base, damaging several buildings in the military's compound, Mohammed said.
Running gun battles
Assailants later located Damaturu and Potiskum, located next to each other about 100km west of Maiduguri, in Yobe state, and engaged in running gun battles with security forces, witnesses said.
Residents heard several explosions, which later turned out to be the bombings of small local churches and a police station.
One of the bombs that ripped through a police office in Damaturu was a suicide blast, a police chief for Yobe state told the AFP on Saturday.
"It was a suicide bomb attack at one of our buildings. The attacker came in a Honda CRV and rammed into the building and explosives exploded," Suleimon Lawal, a police commissioner, told AFP.
Security forces this week started door-to-door searches for weapons in the northeast, after an arms amnesty for fighters expired on October 31. It was unclear whether or not this spate of attacks was a response to that operation.