GENEVA (Reuters) - Congolese security forces and militia have committed atrocities amounting to war crimes and crimes against humanity, including killing and raping women and children, U.N. human rights investigators said on Tuesday.

In a report denouncing “a serious problem of impunity”, the independent experts called on authorities to prosecute perpetrators and provide justice to victims in the insurrection-ravaged Kasai region of central Democratic Republic of Congo.

Marie-Ange Mushobekwa, Congo’s human rights minister, said the government was aware of the report’s contents and she would present its reaction to the accusations at a debate in the Human Rights Council set for next Tuesday.

The armed forces (FARDC) and allied Bana Mura militia opposed the Kamuina Nsapu militia in a partially ethnic conflict that largely ended at the end of 2017.

It was marked by the burning down of villages, the U.N. report said, and Kamuina Nsapu forced child soldiers to decapitate enemies.

“Numerous acts have been committed by the FARDC and the Kamuina Nsapu militia against people not participating directly in the hostilities ... including murder, mutilation, rape and other forms of sexual violence, looting ... and conscription of children under age 15,” the report said.

The conflict in the previously peaceful Kasai region was one of a series of deadly flare-ups to hit Congo around the time long-serving President Joseph Kabila refused to leave power when his mandate expired at the end of 2016.

An election to replace Kabila is now scheduled for December but he has yet to commit to stepping aside, further stoking tensions across the country where millions died in wars around the turn of the century.

In July 2017 a Congolese court convicted seven soldiers for the murder of suspected militia members in Kasai after a video showed soldiers shooting people, some of them young women, at point blank range.

The U.N. report, based on interviews with 524 victims, witnesses and perpetrators, focused on violations in Kasai where the year-long insurrection killed up to 5,000 people and forced some 1.5 million people from their homes.

“Many children have been abducted, wounded, mutilated, detained or executed,” the report said.

“Some saw their parents beaten, decapitated or their mothers raped. Many were forced to fight, put on the front lines without arms or with fake weapons, knives and sometimes traditional rifles. They were forced to kill and decapitate,” it said.

Two U.N. sanctions monitors were killed last March in Kasai while investigating the conflict.

More than a dozen people have been arrested in connection with the crime but separate U.N. experts complained in April that Congolese authorities were obstructing their efforts to assist the investigation.