British troops will take part in the peace-keeping force

A battalion from the Parachute regiment will be the first of 4,000 extra soldiers which Britain has allocated.

On Saturday, the head of Nato's rapid reaction force in the Former Yugoslav Republic of Macedonia, Lieutenant-General Michael Jackson, meets face to face with Yugoslav military officials to discuss the Serb pull-out from Kosovo.

Nato is to demand first that the Serbs switch off their air defences and then come up with a clear timetable for withdrawal.

On Friday UK Prime Minister Tony Blair pledged Britain would provide a "key element" of the peace-keeping force on the ground in Kosovo.

The Paras are famed as a fighting force, but the prime minister denied they would be sent in an offensive capacity.

"It's not an aggressive force, it's entirely in line with the peace-keeping mission that we will have," he said.

The force controlled by Sir Michael Jackson will escort the refugees home

"But it is important to recognise that we are going to be going into a situation where the Serb forces have been very active and it's necessary to have every single part of this special force properly equipped for all eventualities."

The extra UK troops will join Nato's ACE Rapid Reaction Corps already in Macedonia under the control of Sir Michael Jackson.

The BBC's Alva McNicol: The British army is preparing for it's role

About 15,000 forces are already stationed in the Balkan state on Kosovo's border.

Sir Michael joined the Paras in 1970 and commanded the 1st Battalion for two years from 1984. He earned the nickname "Macho Jacko".

Milosevic 'must stand trial'

The UK insisted on Friday that the Kosovo peace deal had not reduced its determination to have the Yugoslav President Slobodan Milosevic tried for war crimes.

Robin Cook: No amnesty for war crimes suspects

Foreign Secretary Robin Cook said President Milosevic would not be "let off the hook" for his ethnic cleansing, despite rising hopes of an end to the conflict.

He said the possibility of an amnesty or immunity had not even been raised by either side in the peace negotiations.

Robin Cook says all war crimes supects must go in the dock

"What we are quite clear about is that as an indicted war criminal like other indicted war criminals he has to face justice," Mr Cook said.

"There can be no lasting peace and settlement in Kosovo without justice against those who carried out the atrocities in Kosovo."

Mr Blair agreed there could be no question of President Milosevic being granted immunity, even if the peace deal was fully implemented.

The BBC's Robin Oakley: Until the Serbs dump Milosevic they will be starved of regeneration

He said the international force to help the refugees return home would also gather evidence against the Serb leadership.

"When we begin that process of going back into Kosovo and we find what has happened and we have a clear picture of what has been done, how many people have disappeared, died, been subject to brutality and barbarity, then we shall have ample evidence of the policies of Milosevic and the evils of ethnic cleansing," he said.

Tony Blair: "We don't want a situation where Mr Milosevic will ever be able to do this again"

While insisting that Nato had never made President Milosevic's removal from office one of its aims, Mr Blair, said it would clearly be in Serbia's interests if he did go.