United Nations report, by the high commissioner for human rights, was leaked to French newspaper Le Monde and strongly suggests human rights abuses carried out by Rwandan soldiers between 1996 and 1998 in Congo could constitute a second genocide.
The UN has not denied it wrote the report but a spokesperson stressed the version given to newspapers is a draft and not final.
Le Monde's story comes from an early version of the report which was circulated to governments in the region. The final report, which sources say differs in nuance and legal terminology but not in substance, is expected to be released in Geneva next week.
"It's a shame about the leak to Le Monde because it creates confusion," said Rupert Colville, spokesman for the UN Office for Human Rights.
'Confusion'Five years in the making, the report which cost US$3m, documents 600 atrocities during a decade of war in the DRC starting in 1993. Thirty-three UN staff spent eight months carrying out research in the DRC, and no incident was included unless verified by two independent witnesses.
Although the focus on alleged "acts of genocide" by Rwandan soldiers and Rwandan-backed forces has drawn headlines, atrocities by many different groups and governments are documented.
"This report is about the past, but it's geared towards improving law and order in the future. The motivation is to tackle impunity, and the first step is to describe what happened," said Mr Colville.
The Rwandan government has stoutly dismissed the findings, with a spokesperson calling the report unhelpful and an "amateurish NGO job".
The motives for the leak have also been questioned by other commentators in Africa.