Government forces have targeted civilians, including women and children, resulting in numerous deaths in central Congo this week and are restricting United Nations peacekeepers' access to the area, the country's UN mission said on Saturday.
Democratic Republic of Congo's army is carrying out operations against the Kamuina Nsapu militia. Clashes between the military and the insurgents have killed hundreds of people and displaced hundreds of thousands since last August.
The UN mission, MONUSCO, said it had received "credible reports of high numbers of deaths" this week in Kananga, the capital of Kasai-Central province, adding that security forces have restricted the mission's freedom of movement.
Congo's government spokesman Lambert Mende denied that the army used excessive force and argued that UN actions needed to be coordinated with Congolese authorities.
"I call for the immediate cessation of violence in Kananga and the Kasai region, and denounce the use of disproportionate force," MONUSCO chief Maman Sidikou said in the statement.
"I further call for an investigation by the appropriate authorities into events in Kananga in recent days, and that those found responsible for any human rights violations be held fully accountable," Sidikou added.
The statement also criticised Kamuina Nsapu militiamen for attacking state institutions and symbols.
Two UN officials, one US citizen and the other of Swedish nationality, were kidnapped by unknown assailants in Kasai-Central this week.