OHCHR has documented summary executions of at least 12 people by the M23 between Jan. 26 and 28 as well as new cases of sexual violence by the Congolese armed forces and members of the pro-government Wazalendo alliance of armed groups, the organisation said in a statement.
Congo's communications minister and a M23 spokesperson did not immediately reply to requests for comment.
As the M23 seeks to advance after capturing the strategic city of Goma this week, UN High Commissioner for Human Rights Volker Turk "calls for an end to the violence and for all parties to uphold their obligations under international human rights law," his spokesperson Jeremy Laurence said in the statement.
Rape has been widely documented as a weapon of war in eastern Congo for decades, fuelling a long-running sexual violence crisis in the region.
"We are verifying reports that 52 women were raped by Congolese troops in South Kivu, including alleged reports of gang rape," Laurence said.
OHCHR cited a report by Congolese officials that at least 165 women were raped by male inmates during a prison break at Goma's Muzenze prison on Jan. 27, as the M23 began its assault on the city of around 2 million people.
Commissioner Turk "is particularly concerned that this latest escalation risks deepening the risk of conflict-related sexual violence much further," Laurence said.
In 2014, the Congolese government launched an action plan to combat sexual violence by members of the military under which hundreds of commanders committed to report cases, but impunity persists.
