Nearly 150 Nigerians have been killed and dozens injured in three days of clashes between Muslim and Christian gangs in the central city of Jos, where police imposed a 24-hour curfew.
The governor of Plateau state sent extra security forces to the state capital yesterday to prevent a repetition of clashes in November 2008, when hundreds of residents were killed in the country's worst sectarian fighting in years.
"On Sunday evening we buried 19 corpses, and 52 yesterday. As of right now, there are 78 at the mosque yet to be buried," said Muhammad Tanko Shittu, a worker organising mass burials at the city's main mosque. Some 90 people had been injured, he added.
This week's violence erupted after an argument between Muslim and Christian neighbours over the rebuilding of homes destroyed in the 2008 clashes. A police spokesman said calm had been restored in most neighbourhoods in Jos, but residents said they could still hear sporadic gunfire and see smoke from burning houses and churches.
The Vice-President, Goodluck Jonathan, who has taken over ceremonial duties from ailing President Umaru Yar'Adua, has ordered troops and the government's top security chiefs to Jos to restore calm.
"I assure you that the federal government is on top of the situation in Jos and the situation is under control," said Ima Niboro, spokesman for the Vice-President.
Mr Jonathan's military order is the first time he has used executive powers since the President left Nigeria for medical treatment nearly two months ago. It was not known whether Mr Yar'Adua, in hospital in Saudi Arabia receiving treatment for a heart condition, had been briefed on the situation.
A Red Cross spokesman said around 2,000 residents had left their homes and taken shelter at a nearby college. Some were injured with machete and gunshot wounds, he said.
There were reports that the clashes had spread to at least seven communities outside Jos, but this could not be independently confirmed.
Dr Aboi Madaki, who works at the Jos University Teaching Hospital, said gunshots and machinegun fire could be heard as early as 4 am and continued for hours afterwards.
"I saw soldiers moving into town and I can see smoke coming from many places," he said.
Nigeria has roughly equal numbers of Christians and Muslims, although traditional animist beliefs underpin many people's faiths.
More than 200 ethnic groups generally live peacefully side-by-side in the West African country, although 1 million people were killed in a civil war between 1967 and 1970 and there have been outbreaks of religious unrest since then.
The US-based Human Rights Watch released a report in July saying around 700 people were killed in the November 2008 clashes, more than three times as many as the official figure given by the government shortly after the violence.