Russia on Wednesday vetoed a draft UN resolution recognizing the Srebrenica massacre as genocide, branding the measure "confrontational" and a setback to reconciliation in the Balkans.

Britain had put forward the draft text, hoping the Security Council would formally recognize Europe's worst atrocity since World War II as an act of genocide for the first time and condemning genocide denial.

Angola, China, Nigeria and Venezuela abstained from the vote on the draft resolution, days before Bosnia is due to mark the 20th anniversary of the murder of 8,000 Muslim boys and men by Bosnian Serb forces in July 1995.

Russian Ambassador Vitaly Churkin called the British-drafted text "not constructive, confrontational and politically-motivated" and argued that it unfairly singled out Bosnian Serbs for war crimes.

"The draft that we have in front of us will not help peace in the Balkans but rather doom this region to tension," Churkin told the council meeting that began with a minute of silence to remember the victims.

British Deputy Ambassador Peter Wilson accused Russia of siding "with those who are unwilling to accept the facts today."

"Genocide occurred at Srebrenica. This is a legal fact, not a political judgment. On this there is no compromise," he said.

Russia, the United States and Britain had been locked in intense negotiations over the past 24 hours to try to avoid a veto and agree on a text.

But Moscow refused to drop its insistence that references to the Srebrenica killings as an act of genocide be scrapped, diplomats said.

Bosnian Serb leaders had called on Russia to use its veto power to block the resolution, arguing that it was "anti-Serb" because it highlighted the killings in the town in the final months of the war.

Bosnian Serb forces commanded by General Ratko Mladic overran the UN-protected safe haven of Srebrenica on July 11, 1995 in what was to become one of the darkest chapters of the 1992-95 Bosnian war.

Mladic's troops brushed aside the lightly armed Dutch peacekeepers and loaded thousands of Muslim men and boys onto trucks before executing them in a nearby forest and burying them in mass graves.