At least 149 people have been killed during two days of violence between Christian and Muslim gangs in the Nigerian city of Jos, officials say.

Mosque workers and Muslim clerics told reporters of the deaths as they prepared for a mass burial.

The death toll has not been verified independently and it is not known how many Christians have died.

Nigeria's vice-president has ordered troops to help police restore order and also dispatched top security officials.

It is believed to be the first time Goodluck Jonathan has used executive powers since President Umaru Yar'Adua left Nigeria for hospital treatment in Saudi Arabia in November.

The clashes broke out on Sunday and have continued since, with reports of gunfire and burning buildings.

A 24-hour curfew has been enforced in the area, which has seen several bouts of deadly violence in recent years.

At least 200 people were killed in an outbreak of fighting between Muslims and Christians in 2008, while some 1,000 died in a riot in 2001.

Violence spreading

The current violence has forced at least 3,000 people from their homes.

Balarabe Dawud, head of the Central Mosque in Jos, told AFP news agency he had counted 192 bodies since Sunday.

Muhammad Tanko Shittu, a mosque worker who was helping to prepare mass burials, told Reuters he had counted 149 bodies.

"On Sunday evening we buried 19 corpses, and 52 yesterday. As of right now, there are 78 at the mosque yet to be buried," he said.

Anglican Archbishop of Jos Benjamin Kwashi told the BBC that the situation was improving in the city centre, where security forces have been deployed.

But the violence spread beyond the city boundaries on Tuesday to neighbouring areas.

Jos is in Nigeria's volatile Middle Belt - between the mainly Muslim north and the south where the majority is Christian or follow traditional religions.

Correspondents say such clashes in Nigeria are often blamed on sectarianism.

However, poverty and access to resources such as land often lie at the root of the violence.

It is unclear what the trigger was for the latest bout of violence.

Plateau State spokesman Dan Manjang told the BBC's Network Africa programme there were reports that it may have started after a football match.

But he said it would be surprising if football was the reason.

Reuters quoted residents as saying the violence started after an argument over the rebuilding of homes destroyed in the 2008 clashes.


ANALYSIS
Shehu Saulawa, BBC Hausa
Jos has long been a time-bomb waiting to explode.

The town is split into Christian and Muslim areas. The divisions have been perpetuated by Nigeria's system of classifying people as indigenes and settlers.

Hausa-speaking Muslims have been living in Jos for many decades but are still classified as settlers, meaning it is difficult for them to stand for election.

The two groups are also divided along party political lines with Christians mostly backing the ruling PDP, and Muslims generally supporting the opposition ANPP.

In Nigeria, political office means access to resources.