Mauritania and Senegal have signed a deal that could allow the repatriation of more than 12,000 refugees.
President Sidi Ould Sheikh Abdallahi has invited all refugees to return
The United Nations refugee agency says it will start a repatriation programme in the next few weeks which will last until December 2008.
Tens of thousands of black Mauritanians fled into exile after ethnic purges in 1989 by Maaouya Ould Sid'Ahmed Taya's Arab-dominated government.
Mauritania's newly elected government has asked those remaining to come home.
The UNHCR, which appealed last August for funds to repatriate the Mauritanians, said it had set up reception centres for the returnees in the southern border towns of Kaedi and Rosso, with contributions from France, Italy and the United States.