Members of the team are reported to have begun taking x-rays of some of the more than 40 dead bodies - found in the village of Racak in southern Kosovo - to determine whether they were killed in a gun battle, or murdered in cold blood.

The head of the team asked a Serbian forensic team, which began work on the bodies on Tuesday, to wait for her team's x-ray unit. Dr Helena Ranta said that under internationally-recognised procedures, x-rays should be first step of any autopsy.

Dr Helena Ranta: "The world has a right to know"

"It should of course have been done before, and that was one of the reasons I suggested they should stop," Dr Ranta said.

"But for some reason or other they didn't, so we have to live with that."

Speaking to the BBC, Dr Ranta said that if there had been "manipulation" of evidence on the bodies, her team would be able to identify traces of interference.

She warned that Serb insistence that the bodies displayed no signs of torture or summary execution was premature. Her team would report within 10 days, she said.

"The world has a right to know what happened there," she said.

Walker to stay?

There are also reports that Belgrade might be prepared to back down over its decision to expel the head of the international verification mission in Kosovo, William Walker.

Mr Walker had been ordered to leave by Thursday evening after blaming Serbian security forces for the killings in Racak.

But the BBC correspondent in Pristina, Jacky Rowland, says that a senior Serbian official, who met a Russian envoy on Wednesday, said that the issue would be solved through compromise and to the satisfaction of both sides.

Mr Walker himself has no intention of leaving Kosovo, his spokesman says.

Jorgen Grunnet told the BBC: "There is no intention of leaving. He will stay here as long as the mission is here."

Nato bombers on heightened alert

Paul Wood reports: This time Nato is serious about military action over Kosovo

Meanwhile, Nato has put fighter-bomber aircraft on a 48-hour alert, and ordered more warships to the Adriatic Sea, in readiness for possible air strikes against Yugoslav forces.

Nato officials have stressed that they want to see a political solution to ethnic Albanian demands for independence from Serbia.

Javier Solana: "The solution has to be political"

Speaking to the BBC, Nato Secretary General Javier Solana said they were backing the international ceasefire monitors already in the province.

But he warned: "If the OSCE has to be withdrawn, there is no question that the only solution is a military type of solution".

The United Nations Secretary-General, Kofi Annan has urged the authorities in Belgrade to defuse the present crisis.

However, Mr Annan said he did not detect any change in their position when he called on them to withdraw their expulsion order against Mr Walker and allow in the chief prosecutor for the International War Crimes Tribunal for Former Yugoslavia, Louise Arbour.

Firing in northern Kosovo

Sporadic fighting is reported to be continuing in northern Kosovo as refugee agencies deliver food to villagers too terrified to return to their homes.

Serb security forces fired an anti-aircraft gun over the village of Shipolje while police took away seven men to a nearby town.