The U.N. peacekeeping mission in DRC expressed frustration over reports of "dozens of children" escaping conscription from the rebel March 23 Movement.
M23 is comprised of former Congolese soldiers who mutinied in early 2012. They're accused of committing war crimes and crimes against humanity during their campaign against the DRC government.
Leila Zerrougui, U.N. special envoy for children and armed conflict, reminded M23 of international laws prohibiting the use of child soldiers under any circumstance.
"I want to remind their leaders that they will be personally held accountable for any violations against children, including the recruitment, re-recruitment or use of children in their ranks," she said in a statement Monday.
M23 leader Bosco Ntaganda surrendered to the International Criminal Court in March to face charges of committing crimes against humanity.
U.N. Secretary-General Ban Ki-moon appointed Martin Kobler to take over as head of the U.N. peacekeeping mission in DRC. He'll succeed Roger Meece, who completes his tenure in July.