KANO: An explosion killed four people in the violence-torn city Nigerian city of Maiduguri as Muslim faithful left a mosque after Friday prayers, the military and residents said.

The blast comes after a series of Christmas attacks blamed on Islamist sect Boko Haram killed at least 42 people, most of them outside a Catholic church near the capital Abuja, and raised fears of reprisals from Christians.

“There was a loud blast near the mosque just after the Friday prayers as people were trooping out of the mosque,” one resident said.

“Everybody scampered to safety, leading to a stampede.”Another resident, Mohammed Bukar, reported four dead and others wounded.“There was confusion following the blast,” he said.

“When the dust settled, I saw four dead people being loaded into a vehicle along with some wounded in the blast.”A spokesman for a military task force in the region confirmed the blast but could not immediately provide details.

“It's true there was a blast near Monday market while people were leaving the mosque. We don't have details yet,” said Lieutenant Colonel Hassan Mohammed.

Boko Haram has carried out scores of attacks in Nigeria, most of them in the northeast. The group's targets in that region have included Muslim leaders.

Thousands have fled Maiduguri fearing further attacks by Boko Haram and heavy-handed military raids, with soldiers accused of killing civilians and burning their homes after bomb blasts.

Christian leaders have expressed mounting frustration over the Nigerian authorities' inability to stop attacks that have killed hundreds of people this year.

They have said they will be forced to defend themselves if the authorities do not address the problem. Amid the mounting concerns over reprisals, a bomb was thrown into an Arabic school on Tuesday in Delta state in southern Nigeria, wounding six children and an adult.

Nigeria, Africa's most populous nation, is roughly divided between a mainly Muslim north and predominantly Christian south.

Violence had been raging even in the days before the Christmas bombings, especially in the northeastern cities of Damaturu, Potiskum and Maiduguri.

Another attack hit the northeast on Wednesday night, when gunmen opened fire and threw explosives at a hotel and open-air bar in the city of Gombe, wounding 15 people, the hotel manager said.

The motive for that attack was not clear, though Boko Haram has often targeted bars. In Damaturu last week, suspected members of Boko Haram carried out attacks followed by a military crackdown that led to clashes. A rights group and police source said up to 100 people were feared dead in the violence.

An emergency official has said an estimated 90,000 people have been displaced in Damaturu.