The joint operations aim at "ensuring peace and security for the civilian population," it said after an emergency meeting, adding that DR Congo's armed forces would set up an "advance headquarters" in Beni.

The meeting -- described as that of a "security council" -- was chaired by head of state Felix Tshisekedi and attended by the head of the UN force, Leila Zerrougi.

The president's office did not say when the joint operations would begin.

The UN mission "will strengthen cooperation with its partners and work closely with the authorities to jointly find solutions for the people of Beni," Zerrougi said in a statement.

Scores of people have been killed in attacks attributed to a notorious armed group, the Allied Democratic Forces (ADF), since the Congolese army launched an offensive in the region on October 30.

Failures to stop the bloodshed have sparked angry demonstrations by local people, targeting the UN mission, MONUSCO, especially.

Before Monday's announcement of joint operations, MONUSCO had made a point of saying that it had had no role in the Congolese army offensive, which had been decided unilaterally.

"MONUSCO cannot engage in operations in a war zone without being asked and without strict coordination with the national army," it said in a tweet.

Uncoordinated action could lead to casualties from friendly fire, it added.