A United States diplomat who led an international observer mission in Kosovo has clashed with former Yugoslav President Slobodan Milosevic at the International War Crimes Tribunal at the Hague. William Walker, former head of the Kosovo Verification Mission, told the court he believed Mr Milosevic had known of Serbian atrocities against ethnic Albanians in the province in 1999. He strongly rejected Mr Milosevic's claim that ethnic Albanian civilians found dead in the village of Racak were casualties of clashes between Serb forces and local rebels on 15 January, 1999. "The first bodies I saw appeared to be elderly men with grey, white hair. All were in civilian clothes," he said. "There was no evidence of a battle having occurred there." In 1999, Mr Walker spoke of a "civilian massacre" carried out by Serb forces - his comments played a key role in forming international opinion that led to Nato's military intervention in Kosovo. In his cross-examination, Mr Milosevic tried to attack the credibility of the ambassador, who he accused of helping the rebels of the Kosovo Liberation Army (KLA).