The United Nations has dismissed allegations of genocide in the eastern Democratic Republic of Congo.
Rebels took Bukavu to 'protect' the Banyamulenge
A rebel commander, who briefly held Bukavu earlier this month, has demanded that the government look into alleged ethnically-based massacres.
UN human rights investigators say they have found no evidence to support General Laurent Nkunda's claims.
The head of the UN team could only confirm the death of four Banyamulenge civilians in recent clashes.
But the UN spokesman said there was widespread and systematic looting and rape committed when Gen Nkunda's forces controlled Bukavu.
"The allegation of genocide happening in Bukavu... is something we can disregard - there is nothing on the ground that lends any credibility to this claim," Robert Ricci head of the UN investigators told the BBC's Focus on Africa programme.
"Genocide is a complex crime, it also includes the intent to destroy in part or all of a particular group of society and from our investigation this intent to kill can certainly not be proved," he said.
Gen Nkunda has threatened to recapture Bukavu if the government does not set up a commission to investigate alleged atrocities against the Banyamulenge ethnic group.
Mr Ricci said that during the recent clashes in Bukavu crimes had been committed by both sides, and he confirmed at least 66 deaths.
Crimes perpetrated by the regular army are already being investigated by the military prosecutor, but the UN has no information that there is any attempt on the side of the rebels to pursue justice, he said.
From the interviews conducted by the UN in Bukavu, patterns are emerging of the systematic rape of children by troops loyal to rebel commanders.
"Soldiers were looking for the youngest female in the household then... (there was) mass rape," Mr Ricci said.
Weeks of insecurity between government loyalists and Gen Nkunda's rebels are proving the most serious threat to DR Congo's fragile peace process aimed at ending years of conflict in central Africa.
Some 17,000 Banyamulenge refugees have since fled to Burundi, terrified of renewed fighting.