A "large number" of peacekeepers have been killed and wounded in an attack in the eastern Democratic Republic of the Congo, the UN's peacekeeping chief said.
Jean-Pierre Lacroix said the attack occurred in North Kivu province.
Mr Lacroix said he is "outraged" by the attack and that medical evacuations are ongoing.
He did not identify the attackers.
The UN peacekeeping mission in DR Congo is the largest in the world and is aimed at calming a number of armed groups in the vast, mineral-rich Central African nation.
Radio Okapi, which is linked to the peacekeeping mission known as MONUSCO, reported that peacekeepers on Thursday repelled an attack by fighters with the Allied Democratic Forces rebel group on a UN base in the Beni area.
The base is home to the peacekeeping mission's rapid intervention force, which has a rare mandate to go on the offensive.
The radio station, citing military sources, said fighting lasted four hours.
It reported that Congolese forces did not intervene because the closest ones were several miles away.