|Outbreaks of violence are frequent near Jos, where the Muslim north meets the largely Christian south [Reuters]
At least 20 people have been killed in clashes in the central Nigerian city of Jos following a protest against the killing of seven Muslims in a nearby village.
The violence is believed to have begun after news spread that Muslims had been killed by Christian youths in an attack on a bus.
Nigerian soldiers fired into the air to disperse youths burning vehicles and tyres in Jos in protest at the killings, villagers said on Saturday.
The Muslims were on their way back from a wedding when they were attacked late on Friday after their bus got lost near a predominantly Christian village, which was at the centre of ethnic and religious clashes last year, witnesses said.
"We received a report ... that youths blocked the road and attacked them inside their bus, killing seven people, while one escaped," said Ahmed Garba, an official from Nigeria's Muslim umbrella group Jama'atu Nasril Islam.
Muslim youths set up burning barricades in parts of the Kwararasa neighbourhood of Jos when news of the attack on the bus spread, but a military taskforce which has been policing the city since last year's unrest was able to disperse them.
Plateau state, of which Jos is the capital, lies in Nigeria's "Middle Belt" where the mostly Muslim north meets the largely Christian south. The region is seen as a potential flashpoint ahead of nationwide elections in April.
Hundreds of people died in clashes between Muslim and Christian mobs in the region early last year and there have been frequent outbreaks of violence since then.
Also on Friday, attackers targeted a rally for a prominent politician in Nigeria's oil-producing region, a military spokesman and witness said.
An AFP correspondent who was at the scene said it appeared around four people were killed, while some local media reported six dead. Authorities confirmed two fatalities.
The attack occurred as Timi Alaibe returned to his home in Bayelsa state from the capital Abuja after resigning from his post as President Goodluck Jonathan's adviser on the oil-rich Niger Delta region.
Alaibe resigned to run for governor in Bayelsa in April elections, and a crowd of supporters welcomed him at the airport on Friday before following him to his home in a convoy. A rally then took place at his home and compound in the town of Opokuma.
The attackers may have infiltrated the crowd at the airport, Lieutenant Colonel Timothy Antigha told AFP.
They are believed to have worn Alaibe shirts being passed out to disguise themselves, he said, adding that some people were attacked inside Alaibe's compound and others outside.
It appeared most of the attackers used machetes and knives, while a gun is believed to have been stolen from a police officer and also used, he said.
"Two people were confirmed dead and scores were injured," Antigha told AFP.
He said 31 people had been arrested and authorities were investigating to determine who was behind the attack.
Aides forced Alaibe inside his home, but he emerged after the attack to address shaken supporters.
"We are not about violence, but change," he said. "What we are about is the peaceful and systematic change of the state in 2011."