Nato spokesman Jamie Shea said that bodies had been removed from two such graves and reburied individually.

Mr Shea said the Serbs' alleged actions were a sign that "the Belgrade authorities are taking the International War Crimes Tribunal seriously", referring to the special court located in The Hague.

He said Nato has reports that the Serbs have dug up mass graves near Glogovac and Lipljan in central Kosovo.

"The villagers of the locality were obliged to rebury the bodies in individual graves.

"We also have reports of efforts to rebury bodies from mass graves at sites where Nato bombing has occurred, and also to rebury bodies in areas formerly controlled by the Kosovo Liberation Army."

The BBC's Nick Childs reports: Mr Shea said the Serbs would not be able to escape the War Crimes Tribunal

"If the Serbs really want to destroy the evidence, all of the evidence, then they are going to have to accumulate a lot of overtime," Mr Shea added.

At the same time, the UK has announced that it is to send a team of police forensic scientists to Kosovo to investigate sites of suspected massacres. Foreign Secretary Robin Cook told the House of Commons that the UK would play a key role in the investigations.

Kosovar men 'missing'

Nato's allegations came as a senior US official said the number of Kosovar men unaccounted for in the province had now reached 225,000 - more than twice the number previously estimated.

David Scheffer, a US ambassador-at-large for war crimes, stressed however that he was not claiming all these men had necessarily been killed by Serb forces or paramilitaries.