MAIDUGURI, Nigeria: Security forces in northern Nigeria on Thursday captured the leader of a militant Islamic sect responsible for days of unrest which have killed more than 180 people and displaced thousands.

Radical preacher Mohammed Yusuf, whose Boko Haram sect wants a wider adoption of sharia (Islamic law) across Africa's most populous nation, was seized after a manhunt involving military helicopters and armed police.

"Mohammed Yusuf has been arrested. He is now at the Giwa barracks (in the northern city of Maiduguri)," Borno state police commissioner Christopher Dega told reporters.

The violence erupted when members of the group were arrested on Sunday in Bauchi state, some 400 km southwest of Maiduguri, on suspicion of plotting to attack a police station.

Yusuf's supporters, armed with machetes, knives, home-made hunting rifles and petrol bombs, then went on the rampage in several states across northern Nigeria, attacking churches, police stations, prisons and government buildings.

President Umaru Yar'Adua, on an official visit to Brazil, spoke by telephone with northern governors and urged traditional and religious leaders to use Friday prayers to warn people about the dangers of such sects.

"The president stated that religious groups such as 'Boko Haram', which seeks to disrupt the peace and security of the Nigerian state, should not be the bride of any true Muslim individual or group," his spokesman Olusegun Adeniyi said.

Nigeria's Muslim umbrella group Jama'atu Nasril Islam has already condemned the violence and backed the security forces.

"Nigerian Taliban"

Boko Haram -- which means "Western education is sinful" -- is loosely modelled on the Taliban movement in Afghanistan. Its members wear long beards and consider anyone not following their strict ideology, whether Christian or Muslim, as infidels.

Its views are not espoused by the majority of Nigeria's Muslim population, the largest in sub-Saharan Africa.

National defence spokesman Colonel Mohammed Yerima said there would be a military "show of force" on Friday to reassure civilians that they would be protected.

Maiduguri has borne the brunt of the fighting. Local residents said they were still too afraid to venture out despite assurances from the authorities.

"This city is like a battlefield," Muhammed Yakubu, a resident of Maiduguri and a local journalist, told Reuters.

Yar'Adua has said intelligence agencies had been tracking the group, sometimes referred to as the "Nigerian Taliban", for years and that its members were procuring arms and learning to make bombs to force their views on Nigerians.

He ordered the security forces to take all necessary action to "contain them once and for all".

Police in Maiduguri said the security forces had killed 90 sect members on Monday alone. Eight police officers, three prison officials and two soldiers were also killed.

In neighbouring Yobe state, police said they had recovered the bodies of 33 sect members after a gun battle near the town of Potiskum on Wednesday. More than 50 people were killed in the initial fighting in Bauchi on Sunday.

Police said they freed 95 women and children on Wednesday being held by the sect in Maiduguri. Its members believe their wives should not be seen by other men and their children should receive only a Koranic education.

The violence in the north is not connected to unrest in the Niger Delta in the south, where militant attacks have prevented Nigeria from pumping much above two-thirds of its oil capacity. The delta's main militant group has condemned the violence.