The March 23 movement in the Democratic Republic of Congo pulled back from Goma, the capital of North Kivu province, last month. U.N. officials said some rebel forces remained in the area, noting sexual violence was carried out against the civilian population in the area.
Rupert Colville, a spokesman for the U.N. High Commissioner for Human Rights, said Friday that members of the Congolese military were behind atrocities as well.
"We are highly concerned by these events, which once again are devastating the lives of civilians in eastern DRC," he said. "We are appalled that yet again women and girls are being targeted by a variety of groups, including the national army that is supposed to protect them."
A U.S. State Department official this week said Washington would "respond appropriately" to foreign support of rebel movements on the ground in DRC. The Rwandan government is suspected of backing M23, an allegation it denies.
"We urge parties to the conflict to ensure strict respect for human rights and international humanitarian law," said Colville. "Further measures should be taken as a matter of priority to identify alleged perpetrators of such violations and to hold them to account."