The UN says army troops have been looting and targeting civilians in villages in eastern Democratic Republic of Congo.
More than 250,000 people have been displaced by the recent violence, triggering a major humanitarian crisis belying the volcanic region's natural beauty.
The rebels have been seizing ground from the Congolese army and the fighting has hampered aid efforts.
Rebel leader General Laurent Nkunda says he will topple the government in Kinshasa unless it agrees to talk to him. It refuses, calling him a war criminal.
Thousands of people have fled to the regional capital, Goma, which is defended by UN peacekeepers.
Aid agencies fear a cholera epidemic could break out if the fighting continues and people remain without proper sanitation.
About 70,000 people are living
in makeshift camps in Kibati just outside Goma.
But some people have been returning to their homes in rebel-held, despite the dangers, saying there is not enough food or shelter for them in Goma.