A 550-page report by the U.N. High Commissioner for Human Rights estimates that tens of thousands of people were killed, and numerous others were raped, mutilated or otherwise victimized from 1993 to 2003.
"Violence in the DRC was, in fact, accompanied by the apparent systematic use of rape and sexual assault, allegedly by all combatant forces," the report said.
Kenneth Roth, executive director for Human Rights Watch, said the report highlights the "cycle of atrocities" committed in the Great Lakes region of Africa.
"This detailed and thorough report is a powerful reminder of the scale of the crimes committed in Congo and of the shocking absence of justice," he said in a statement.
Navi Pillay, the high commissioner for human rights for the United Nations, blamed Rwandan forces for playing a role in the atrocities. The Rwandan government reacted to an August draft of the document by saying it would pull its troops out of U.N. peacekeeping missions in the region.
"These events can no longer be swept under the carpet," added Roth.