The United Nations refugee agency says it has credible reports that camps for displaced people in the eastern Democratic Republic of Congo have been forcibly emptied, looted and burned.
The camps, housing more than 50,000 people, are in an area now controlled by rebels following their advance towards Goma, the capital of North Kivu province.
In total, aid groups say they are struggling to reach about 250,000 people fleeing fierce fighting between government and rebel forces. The Congolese government has refused to negotiate with the rebels.
Forces loyal to rebel general Laurent Nkunda say they are protecting the Tutsi minority. An acute lack of food and water in Goma has led thousands of people who had sought refuge there to flee north.
Fighting between the two sides resumed in August after a peace deal collapsed. Human rights monitors have accused government troops of raping and murdering civilians in Goma.
The UN has the world's biggest peacekeeping force, 17,000-strong, in DR Congo, which is about the size of western Europe, but only 6,000 troops are in the east because of unrest in other
Overstretched UN troops can only hope a tense ceasefire holds in and around Goma, but aid agency chiefs say the situation remains highly volatile.