Amnesty International accused the M23 rebel group of killing, torturing, and forcibly disappearing civilians in eastern DRC.
Their investigation interviewed 18 former detainees, nine of whom reported being tortured by M23 fighters in Goma and Bukavu.
Amnesty International’s Tigere Chagutah stated the M23 brutally punishes perceived opponents to intimidate others.
He urged pressure on Rwanda to end its support for the M23.
The Manzi Foundation, a local NGO, suggested the accusations might be inaccurate and misleading.
Amnesty International called for the immediate release of arbitrarily detained civilians and disclosure of the forcibly disappeared.
They also demanded humane treatment, access to lawyers and families, and access for independent monitors.
Eight detainees reportedly witnessed others die in detention, likely from torture and harsh conditions.
Former detainees said the M23 accused them of supporting the Congolese army or government.
Last month, the M23 agreed to work toward a truce with the Congolese government.
The UN reports about 1 million people displaced in eastern Congo since late January.