Jose-Maria Aranaz, the UN human rights director in the country, was speaking just a day the UN said another 38 suspected mass graves had been discovered in this central part of the Democratic Republic of Congo.
“With more than 80 mass graves identified … it is essential that the inquiry goes beyond those who physically did it and identifies command responsibilities at the military and political level,” said Aranaz.
Aranaz dismissed as “unconvincing” the suggestion that rogue elements of the security forces were responsible for the violence.
“We have to stop the killing,” he said.
The international community has voiced alarm over the violence, which has claimed the lives of more than 3,000 people, according to statistics compiled by the Roman Catholic church.
The UN’s MONUSCO peacekeeping mission in the country had previously spoken of “more than 400 dead” while about 1.3 million people are thought to have fled their homes.
An investigative mission this month found the latest mass graves in the Diboko and Sumbula areas of the Kamonia territory, the UN said.
The violence began last year when a tribal chieftain known as the Kamwina Nsapu openly challenged the authority of President Joseph Kabila’s government.
That provoked a crackdown by security forces and the Kamwina Nsapu was killed in a police operation in August 2016.
His armed followers fight on and some believe that their leader is still alive because authorities failed to give his body appropriate funeral rites.
In February MONUSCO accused the Kamwina Nsapu militia of “atrocities… including the recruiting and use of child soldiers,” but also condemned “a disproportionate use of force” by government troops.
Two western experts sent to investigate the conflict by UN Secretary-General Antonio Guterres went missing in March. Their bodies were found in a shallow grave by peacekeepers a fortnight later.
The government blamed the tribal militia for their murders.
On Tuesday, the United States urged the UN Security Council to punish those responsible for the flareup of violence. It also threatened sanctions against the Democratic Republic of Congo if elections are not held this year.
President Joseph Kabila’s mandate is due to end in December.