Islamist militants seeking to impose a Taliban-style regime in northern Nigeria launched attacks Monday on police in three towns, expanding a two-day campaign of violence that has killed at least 55 people, police and witnesses said.

Trouble began Sunday when militants attacked a police station in the northern city of Bauchi, leaving dozens dead in gunbattles with police. On Monday, militants launched a wave of attacks in three more states, targeting the towns of Maiduguri, Damaturu, and Wudil in the predominantly Muslim North, police and residents said.

National police chief Ogbonnaya Onovo put the overall toll at 55 dead at least — 50 militants and five police officers.

A journalist for the local Compass newspaper in Maiduguri, Olugbenga Akinbule, said he saw the bodies of about 100 Islamist militants shot in gunbattles with police in the town, where some of the worst violence occurred. Authorities did not confirm that toll.

Nigeria has been sporadically wracked by sectarian clashes since 12 of the country's 36 states began adopting Islamic law, or Shariah, in the north in 1999.

The radical sect known as Al-Sunna wal Jamma, or "Followers of Mohammed's Teachings" in Arabic, comprises mainly young Nigerians who want to create a Taliban-style state based on a strict interpretation of Shariah Law and the Quran. The group first came to prominence with a wave of similar assaults on New Year's Eve 2003. More attacks followed in late 2004, but little has been heard about the sect since.

Residents in the North also refer to the Islamists as "Boko Haram," which means "Western education is sin" in the local Hausa dialect. Onovo referred to the militants as Taliban, though the group has no known links to Taliban fighters in Afghanistan.

A local newspaper, Daily Trust, quoted the leader of the sect, Ustaz Mohammed Yusuf, as saying his followers are ready to die to ensure the institution of a strict Islamic society.

"Democracy and (the) current system of education must be changed, otherwise this war that is yet to start would continue for long," he said.

Onovo vowed that police would arrest the group's leaders.

"This a fanatical organization that is anti-government, anti-people. We don't know what their aims are yet; we are out to identify and arrest their leaders and also destroy their enclaves, wherever they are," Onovo said.

In Damaturu, capital of Yobe state, militants bombed a police station, said national police spokesman Emmanuel Ojukwu.

In Kano state's Wudil district, militants attacked another police station, according to local police spokesman Baba Muhammad. He said three militants were killed and two police officers were wounded in a shootout, and 34 militants were arrested.

In Maiduguri, the capital of Borno state, militants battled police for hours. Onovo said he had sent "reinforcements to our men in Maiduguri to be able to cope with the situation." Akinbule said militants attacked a police headquarters, burned 10 houses inside the police compound, and freed prisoners from a state prison.

Nnamdi K. Obasi, a Nigerian analyst with the International Crisis Group, said trouble has been brewing for a while.

He said police in Maiduguri stopped some motorcycle-riding members of a funeral procession carrying the body of a sect member two months ago because they were not wearing helmets. A fracas ensued and police shot and killed 14 members of the group, prompting Yusuf to vow retaliation, Obasi said.

Police have been carrying out operations against the group. Last week in Biu, about 200 kilometers (125 miles) south of Maiduguri, they raided a militant compound and found homemade bombshells, explosive material, knives, machetes and guns, and arrested nine militants.

On Saturday, police in Maiduguri raided another house being used by the militants after a homemade bomb exploded there accidentally, killing one militant and injuring another, according to Onovo, who said police "recovered many bags of explosives and different types of dangerous weapons" from the house.

Obasi said the dead militant was a senior leader of the sect who group members believe state security forces assassinated. "Word went around their network that the police were carrying out pre-emptive searches, and this has led to the attacks since Sunday," Obasi said by telephone from Kearney, Nebraska.

More than 10,000 Nigerians have died in sectarian violence since civilian leaders took over from a former military junta in 1999, though in recent years such violence has eased.

Nigeria's 140 million people are nearly evenly divided between Christians, who predominate in the south, and primarily northern-based Muslims. Shariah was implemented in a dozen northern states after the country returned to civilian rule in 1999 following years of oppressive military regimes.

Obasi said, however, that Shariah was never strictly imposed, and politicians had used the promise to do so to consolidate their hold on power and attract funding from the Middle East.

The Islamist sect has been able to expand quietly since 2004, fueled by deepening poverty and lack of development.

"You find Islamic leaders coming forward to say, 'We've never gained anything from Western models of governance or education, and unless we go back to the society prescribed by the Quran, nothing will get better,"' Obasi said.