The ICC in its unsealed indictment accuses Bosco Ntaganda, a former military commander and rebel leader, of crimes committed in the Democratic Republic of Congo. The ICC in its 2008 indictment said there was "reasonable grounds to believe" he played a direct role in conscripting child soldiers.
Human Rights Watch said that since January, Ntaganda was linked to the assassination of at least eight people and the arrest or disappearance of several more.
Anneke Van Woudenberg, a senior researcher at Human Rights Watch, said in a statement that by remaining free, he was insulting Congolese authority.
"He is a threat to the people of eastern Congo and is making a mockery of the Congolese government's policy of zero tolerance for human rights abuses," she said.
French authorities said Monday they arrested Callixte Mbarushimana, the executive secretary of the Democratic Force for the Liberation of Rwanda, or FDLR.
Human Rights Watch said the FDLR is linked to "widespread and vicious attacks" against civilians in response to United Nations-backed military operations launched in the area in 2009.
The U.N. Security Council was called on to consider targeted sanctions against the FDLR and the Congolese Mai Mai militia for their role in the mass rapes during the summer.