GENEVA – Congo’s armed forces and Rwanda-backed M23 rebels have committed crimes including gang rape, sexual slavery, torture, killings of civilians and other “horrific” atrocities in eastern Congo over the last year, the U.N. human rights office said Friday. It said the governments of both countries bear responsibility.

A new report by a fact-finding team of experts that visited the region between March and August warned of the prospect of war crimes and crimes against humanity that may have been committed since late 2024 and since the decades-long conflict in the central African nation escalated in January, when M23 fighters seized the strategic eastern city of Goma.

“The atrocities described in this report are horrific,” Ravina Shamdasani, spokesperson for the United Nations’ office, told reporters in Geneva, quoting High Commissioner for Human Rights Volker Türk. “It is heartbreaking and deeply frustrating to witness once again the dehumanization of the civilian population by those in power who are failing in their responsibilities.”

The U.N. Human Rights Council is expected to consider the report during its upcoming monthlong session that opens Monday.

The fighting has killed some 3,000 people, raised the fears of a wider regional war, and created one of the world’s most significant humanitarian crises. Widespread human rights violations during the conflict have been reported for years and there has recently been an increase in reports of sexual violence — mostly against women and girls.

The report found that M23 rebels had carried out summary executions, torture, detention, enforced disappearances and forced recruitment, affecting thousands of civilians perceived as opposing the group, its authority or recruitment.

“Rapes were repeated over prolonged periods, often in conjunction with additional acts of physical and psychological torture and other ill-treatment, with a manifest intent to degrade, punish, and break the dignity of victims,” the report said.

Shamdasani said “the findings of this report drive home just how serious the situation is” and the “systematic” nature of rights violations and abuse.

The report also documented violations committed by Congo’s armed forces, known by the French-language acronym FARDC, and affiliated armed groups such as Wazalendo. They included deliberate killings of civilians, widespread use of sexual violence, mainly rape and gang rape against women and girls, and looting.

“Perpetrators operated in large groups and in multiple localities simultaneously, in a manner that reflected recurring patterns of rape and looting, rather than isolated acts,” the report said.

The rights office said the governments of both countries bear responsibility.

“DRC and Rwanda bear responsibility for their support to armed groups with known track records of serious abuses, and for failing to meet their obligations to take all measures to ensure respect for international humanitarian law and to protect civilians from serious harm,” it said.

A peace deal mediated by the United States was signed in June, but the report said it has not led to enough accountability for crimes or support for victims.