Human Rights Watch said it has evidence to suggest that Rwanda military officials have provided weapons, ammunition and hundreds of fighters to support Ntaganda's mutiny, which he launched in April.
"The role played by some Rwandan military officials in supporting and harboring an ICC war crimes suspect can't just be swept under the rug," Anneke Van Woudenberg, senior Africa researcher at Human Rights Watch, said in a statement.
"The Rwandan government should immediately stop all support to Ntaganda and assist in his arrest."
Ntaganda's forces were integrated into the Congolese military under the terms of a 2009 peace deal. Wanted for war crimes since 2006, Ntaganda is accused of conscripting child soldiers to his ranks.
The rights group said Rwandan forces have allowed Ntaganda to enter their territory to flee authorities in the Democratic Republic of Congo. The group also says some military recruits were summarily executed after attempting to flee the service of the rebel general.
"Permitting Ntaganda to move in and out of Rwanda without fear of arrest sends a message that Rwanda is not serious about helping deliver justice to victims of the war crimes he and his troops have committed," added Van Woudenberg.