Rwanda, whose troops are at the centre of the most serious accusations, said it categorically rejected the report after it failed to have it suppressed while Burundi said it was designed to destabilise the region.
The Democratic Republic of Congo’s government said it was “appalled” by the details in the report and demanded justice for the victims.
“While it neither aims to establish individual responsibility, nor lay blame, the report – in full candour – reproduces the often shocking accounts by victims and witnesses of the tragedies they experienced,” Navi Pillay, the UN high commissioner for human rights, said in the preface to the report.
“The report is intended as a first step towards the sometimes painful, nonetheless essential, process of truth-telling after violent conflict,” she added.
The report, reworded in parts after a leak, said the “apparent systematic and widespread attacks... reveal a number of inculpatory elements that, if proven before a competent court, could be characterised as crimes of genocide”, pointing in particular to attacks by Rwandan troops during 1996-1997.
“It was not a question of people killed unintentionally in the course of combat, but people targeted primarily by AFDL (Alliance of Democratic Forces for the Liberation of Congo)/APR (Rwandan Army)/FAB (Burundi army) and executed in their hundreds,” it added.
The Rwandan government reacted furiously, saying it “categorically rejected” the report.
The accusations of genocide are particularly contested by Kigali as its government has based much of its legitimacy on being the force that stopped the genocide in Rwanda in 1994.
Rwandan President Paul Kagame, who earlier dismissed the report’s claims as “absurd”, was at the vanguard of the Rwandan force which drove the Hutu militias behind the 1994 genocide in his homeland across the border into eastern DR Congo.
The Burundi government, whose troops were also accused of abuses, said the report was aimed at “destabilising the entire region”.
The report’s language is, however, less assertive than in an earlier leaked draft compiled by investigators.