The United Nations says 50,00 people have fled Sudan's troubled Darfur region in the past week.
U.N. officials say the exodus is the largest in many years and is the result of renewed tribal conflict in the region.
Refugees have told aid workers that some villages have been completely destroyed.
The United Nations refugee agency says a total of 74,000 refugees have fled from Darfur to neighboring Chad in the past two months. The agency did not say how many people have died in the recent fighting.
In February, a Sudanese lawmaker said tribal violence in Darfur that month left more than 500 people dead.
Conflict has ravaged Darfur since 2003, when mainly non-Arab rebels took up arms against the Arab-led government.
That conflict has eased in recent years but battles between tribes have now become more prevalent.
The United Nations says 10 years of violence in Darfur have left more than 300,000 people dead and forced close to 2 million civilians from their homes, creating a humanitarian disaster.