Fifty villages have been "torched" since 3 April, Mr Shea said. He also suggested that Serb families were helping soldiers and special police to weed out ethnic Albanians by painting a Cyrillic "S" on their front doors - showing "Serbs live here".
Nato was also alarmed, he said, by reports that the Serbs were pushing back Kosovar refugees by closing borders to the south and telling them to return to their homes. He said the indications were that President Milosevic might be trying to create a further internal humanitarian crisis inside Kosovo now that the international community was on the point of coming to terms with the external crisis. "We don't have much evidence," Mr Shea admitted, "but if it is true it would be very alarming indeed." He added: "I hope the Serbian government is not playing poker with people's lives."
He said that refugees who were turned back at the border would be forced back into "a wasteland" without water and food and where homes and villages had already been looted.
Some Nato diplomatic sources suggested that the Serb strategy might be the precursor to moves towards a divided Kosovo - part of which would remain inside Yugoslavia, part of which would become independent. "This might explain why he is apparently letting some of them stay," said one source.
Mr Shea said Nato was attempting to acquire corroboration for 22 alleged atrocities and a further 27 alleged incidents. Three mass graves had been identified from refugee accounts at Drenica, Malisevo and the Pagarusha valley.
"Every day brings in more evidence," Mr Shea said, adding that there were also reports of Serb forces using Albanian men as human shields in covering artillery attacks on KLA forces.
The total number of displaced people since the conflict began in March 1998 has crept past 910,000. On Tuesday alone 42,000 people crossed into neighbouring countries. Mr Shea said the international community was "rapidly getting a grip" on the refugee situation and was on the way to "stabilising" Macedonia and Albania.
The US Defence Secretary, William Cohen, in Brussels yesterday, accused the Serbs of perpetrating "one of the most brutal assaults on humanity we have seen since World War Two". He repeated Washington's rejection of any settlement that rewarded the Yugoslav President. In response to reports that the Serb army was hunkering down and hiding its tanks, Mr Cohen said the Nato air campaign would become more aggressive.Reuse content