Forces with the rebel March 23 movement agreed to pull out of Goma, the capital of North Kivu province in DRC. The rebel group mutinied in early 2012, saying the government in Kinshasa had reneged on peace agreements.
Moustapha Soumare, the United Nations' humanitarian coordinator for DRC, said at least 130,000 people have been displaced by ongoing conflict in the region.
"Goma has a population of nearly 800,000 and while awaiting that the Congolese authorities regain full control over the city, one cannot exclude the risk of looting or renewed violence," he said in a statement. "I call on all parties to honor their obligations under international humanitarian law to protect all civilians."
M23 rebels are accused of war crimes. The International Criminal Court called for the immediate arrest of rebel leaders when Goma was captured last month.
The Rwandan government is accused of supporting Congolese rebels. The government in Kigali denies the allegations, though the British government announced it was withholding financial aid in response to the concerns.