The M23 rebels have summarily executed 44 people and raped at least 61 women since March 2013, reported Human Rights Watch.
The findings are based on more than 100 interviews since March, which included former M23 fighters who left the movement between late March near the Congo-Rwanda border.
The findings also suggested that Rwandan authorities were heavily involved in supporting the rebels,
“Not only is Rwanda allowing its territory to be used by the abusive M23 to get recruits and equipment, but the Rwandan military is still directly supporting the M23,” said Africa director at Human Rights Watch.