By Stephanie Nebehay

GENEVA, May 11 (Reuters) - Sudan has asked a United Nations team to travel to its troubled Darfur region to evaluate the status and needs of 45,000 men, women and children who have crossed over from Chad, the U.N. refugee agency said on Friday.

The Chadians, who have crossed the border in the last three months, appear to be mainly Arab nomads, but it was not clear whether they were refugees fleeing conflict in Chad or had just crossed the volatile border, UNHCR spokeswoman Helene Caux said.

"The Sudanese government has asked us to provide assistance. An assessment mission of different U.N. agencies is trying to go at the weekend," Caux told Reuters in Geneva.

"At this point we don't know who they are and we need more information -- are they refugees or nomads, have some been fighters in Chad? We have to determine their status," she said.

Sudanese authorities have told the U.N. High Commissioner for Refugees (UNHCR) that the Chadians have gathered at the border near Foro Baranga, in West Darfur, according to Caux.

Sudan and Chad signed a reconciliation deal last week, pledging to cooperate with the United Nations to stabilise Sudan's Darfur region and the neighbouring areas of Chad.

The United Nations says some 200,000 people have died and more than 2 million have fled their homes since the Darfur conflict flared in 2003 when rebels took up arms against the government, accusing it of neglect. Sudan says only 9,000 have perished.

Chad has repeatedly accused Sudan of backing rebels in Chad and of supporting attacks in Chad by Janjaweed militia based in Darfur. The Sudanese government calls the Janjaweed outlaws and says it has no ties to them.

The UNHCR said last month that up to 400 people had been killed in an attack on two villages in eastern Chad, which survivors said was carried out by Sudanese and local Janjaweed militia aided by Chadian rebels.

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