More than 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, residents said.
The governor of Plateau state sent extra security forces to the state capital 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 80 at the mosque yet to be buried," said Muhammad Tanko Shittu, a worker organising mass burials at the city's main mosque, adding 90 people had been injured.
But official police figures were significantly lower with 20 people dead, 40 injured and 168 arrested since Sunday.
"Any other figures being bandied by people could be done with mischief aimed at aggravating the situation," said Yemi Ajayi, spokesman for the national police in the capital Abuja.
This week's violence erupted after an argument between Muslim and Christian neighbours over the rebuilding of homes destroyed in the 2008 clashes.
The fighting is unlikely to have a big impact on sub-Saharan Africa's second biggest economy. Its oil industry is in the south and its banking sector mainly in the commercial hub Lagos.
Police 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.
Vice-President Goodluck Jonathan ordered troops and top security chiefs to Jos to restore calm, in his first use of executive power since President Umaru Yar'Adua left Nigeria for treatment at an overseas hospital nearly two months ago.
"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.
It was not known whether Yar'Adua, who is receiving medical treatment in a hospital in Saudi Arabia, 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.
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.
Reuters