BUJUMBURA, Burundi, May 7 (UPI) -- A recent surge in violence between rebel groups and the Burundi government has prompted calls for the release of children recruited to fight in the conflict.

The U.N. secretary-general's special representative for children and armed conflict, Radhika Coomaraswamy, is calling for the release of an estimated 500 children who have been recruited by the rebel group Palipehutu-FNL of Agathon Rwasa.

Coomaraswamy says the recent surge in fighting, despite a comprehensive cease-fire agreement signed in 2006, has created an urgent situation that is specifically endangering children, the United Nations reported.

"The outbreak of renewed fighting by the Palipehutu-FNL of Agathon Rwasa proves once again the need to quickly separate all children from fighting forces even before a final peace agreement is signed," Coomaraswamy said in a news release.