GENEVA (Reuters) - Killings, rapes and other barbaric violence committed by an ethnic armed group in northeastern Democratic Republic of Congo against a rival group may amount to crimes against humanity and possibly even genocide, the United Nations said on Friday.

The attacks in Ituri province have mostly targeted Hema herders, who have long been in conflict with Lendu farmers over grazing rights and political representation.

Lendu armed groups have carried out systematic and widespread attacks, trying to “inflict lasting trauma” on the Hema and clear them from what they deem to be their ancestral lands, the U.N. human rights office said in a report.

“The widespread nature of the organization, the systematic nature, is certainly characteristic of crimes against humanity,” U.N. human rights spokesman Rupert Colville told a briefing.

“The burden of proof of genocide, the intent to destroy a whole part of a population, is far more difficult to prove.”

Lendu groups have acquired more firearms after seizing them from the military, U.N. investigators said.

“The barbarity that characterizes these attacks – including the beheading of women and children with machetes, the dismemberment and removal of body parts of the victims as trophies of war – reflects the desire of the attackers to inflict lasting trauma to the Hema communities and to force them to flee and not return to their villages,” the report said.

“Certain elements constituting genocide” - a rare designation under international law - may be present, it said.

The FARDC army and police have failed to stop the violence and have themselves carried out executions, rapes and arbitrary arrests, it said. Congolese authorities must deploy more security forces and investigate abuses, it added.

At least 701 people have been killed and 168 injured during inter-ethnic violence between the Hema and Lendu communities in Djugu and Mahagi territories from December 2017 to September 2019, the report said. At least 142 people have suffered acts of sexual violence, it added.

Most victims are from the Hema community, but the U.N. investigators said they had also documented acts of reprisals by some Hema, including the burning of villages.

Nearly 57,000 Congolese have fled to Uganda while more than half a million have been displaced in their homeland, it said.