A confidential report by a United Nations panel of experts says refugees from Burundi received training from Rwandan military personnel last year with the ultimate goal of removing Burundian President Pierre Nkurunziza from power.

The report, seen by The Associated Press, says about 400 Burundian refugees were recruited and trained in small arms, hand grenades and mortars, among other weaponry.

The panel of experts is charged with monitoring sanctions against Congo, which borders Burundi. The experts say they spoke to 18 Burundian combatants in Congo's South Kivu province who said they had been recruited at a refugee camp in eastern Rwanda in May and June 2015.

The combatants said their numbers total four companies of 100 recruits each.

The report also says six of the 18 Burundians interviewed were children.