"Following the renewal of fighting in the east of the Democratic Republic of Congo, I would like to remind all those involved that I am monitoring developments on the ground with the utmost vigilance," Fatou Bensouda, chief ICC prosecutor, said in a statement.
Members of the March 23 Movement and other regional rebel groups are fighting against the DRC military, which is supported by a so-called intervention brigade of U.N. peacekeepers. M23 is comprised of former rebels integrated into the military who mutinied last year, saying the government wasn't honoring its commitment to a 2009 peace deal.
M23 in October fired twice on U.N. helicopters patrolling eastern DRC. A Tanzanian peacekeeper was killed in clashes with the rebel group last weekend.
Rebel groups in the region are suspected of committing war crimes. M23, in particular, has been accused of recruiting child soldiers.
"Justice must be done to enable the DRC to break free of this downward spiral of violence," Bensouda said. 'I will not hesitate to broaden my investigations to include any new allegations of crimes within the court's jurisdiction and, if necessary, to prosecute those responsible."