Dirty and exhausted, the refugees sought police escorts to take them to neighbouring Bauchi and Nassarawa states fearing that Christians in surrounding villages would try to kill them as they left, a Red Cross worker said. 

"Thousands of displaced people have crossed into Bauchi from Yelwa and the surrounding area," said Umar Mairiga, who led a Red Cross team to the area on Thursday. 

"They are using police escorts to take them out of the area completely because militant Christians have mounted roadblocks on the roads," he added. 

Origin of conflict

The origin of the conflict between the Christian Tarok and the Muslim Fulani is rooted in their competing claims over the fertile farmlands of Plateau state in central Nigeria. 

But it has been stoked by religious hatred and the sense among the Christian population that Muslims are outsiders in Plateau. 

Survivors of the Yelwa massacre said they had buried 630 corpses in several mass graves around the remote market town after Sunday's attack. It was not possible to confirm the figure independently, but a senior policeman spoke of "hundreds" dead. 

Presidential spokeswoman Remi Oyo said 630 dead was an exaggeration, but offered no further information. 

Vying for control

The Yelwa attack was the latest in a three-month-long conflict between Muslim and Christian groups vying for control
of Plateau state. 

The attack was the  latest  in a
three-month-long conflict

Before Sunday, the fighting had already killed at least 350 people on both sides, according to witnesses, military and Red Cross sources. The government routinely does not confirm tolls in religious fighting for fear of reprisal attacks by those sympathetic to the victims. 

Nigeria's population of 130 million is split roughly equally between Muslims and Christians. 

More than 5000 have been killed in religious and political violence since 2000, when 12 northern Nigerian states decided to establish Sharia Islamic law. 

Ethnic fighting in Nigeria, the world's seventh largest oil exporter, has hit oil exports in the past, but Yelwa is hundreds of miles from any oilfields. 

House to house

Armed with assault rifles and machetes, Christians went from house to house in Yelwa slaughtering men, women and children, survivors said. Some corpses showed signs of mutilation and sexual abuse, a Reuters witness said. 

"The people doing the shooting were retired police or military. That's why we want a judicial inquiry to get to the root of the genocide"

Justice Abdulkadir Orire,
Secretary-general of Jama'atu Nasril Islam

"It was an organised killing," said Justice Abdulkadir Orire who, as secretary-general of Jama'tu Nasril Islam, is a leader of Nigeria's 60 million Muslims. 

"The people doing the shooting were retired police or military. That's why we want a judicial enquiry to get to the root of the genocide," he said. 

Mairiga said skirmishes and isolated killings were still happening in villages around Yelwa, despite a heavier presence of riot police in the area. 

Needs of the injured

Mairiga, who led the first medical team to visit the town on Thursday, said he was overwhelmed by the needs of the injured. 

"There are so many people with gunshot wounds," he said. "Some had bullets in their heads, others in their tummies or shoulders." 

Mairiga said the local government had put medical supplies in the general hospital at Shendam, a predominantly Christian
village about 10km from Yelwa, but the Muslim victims were too afraid to go there. 

"The people in Yelwa think they will be massacred if they go
there," Mairiga said.

Yelwa had already witnessed one of the worst atrocities of the conflict in February, when Muslim militia killed almost 100 Christians, including 48 killed in a church that they later burned.