Former rebels who integrated into the national army mutinied early this year, forming the March 23 Movement after saying the government in Kinshasa failed to implement a 2009 peace deal. Led by war crimes suspect Bosco Ntaganda, M23 forces this week seized control of Goma, the provincial capital of North Kivu province along the border with Rwanda.
Ntaganda is accused of war crimes by the ICC, including the use of child soldiers. ICC Chief Prosecutor Fatou Bensouda said her office was investigating allegations that M23 leaders in Goma had threatened the civilian population.
Her office said Ntaganda, along with Sylvestre Mudacumura, commander of the Democratic Forces of the Liberation of Rwanda, are "actively" involved in violence plaguing eastern Democratic Republic of Congo.
"Bosco and Mudacumura must be arrested, now," a statement from her office read. "The continued violence in the region reflects the terrible cost of impunity to victims."
Madacumuar was in charge of Rwanda forces during the 1994 genocide. He's wanted by the ICC for ordering war crimes in eastern DRC provinces.
Neighboring Rwanda and Uganda are accused of supporting rebel forces in DRC, allegations the governments deny.
BBC correspondents on the ground in Goma said rebel forces there were encouraged by residents to advance on the DRC capital Kinshasa.