Mr Cook said he was "determined that those who are responsible for turning Kosovo into a slaughterhouse" should be brought to justice.

The UK had evidence of 50 separate incidents involving Serb forces operating in Kosovo over the last month alone, he said.

In what he described as a "rare step", he promised to hand over British evidence of war crimes to an independent United Nations-mandated tribunal under Canadian judge Louise Arbour.

Robin Cook: "Sustained campaign of brutality going back over a year"

"The scale of inhumanity required to achieve [Serbian] President Milosevic's ambition numbs the imagination," he said, adding that "a sustained campaign of brutality" in Kosovo had gone on for more than a year.

Citing the week of 29 January to 5 February, Mr Cook described a list of atrocities, including the discovery of bodies of 24 Kosovo Albanians found in and around a minibus "riddled with bullets".

Robin Cook: "Those responsible for turning Kosovo into a slaughterhouse should be brought to justice"

He said the intention of the tribunal was not just to bring the "death squads" who had "burned, raped and shot their way across Kosovo" to justice, but also "those who gave the orders".

Mr Cook said a British official had been appointed to liaise with Judge Arbour in providing existing documentation and gathering new evidence of war crimes.

The foreign secretary suggested that Kosovo Albanian refugees would play a major role in investigations, saying that "each carries the evidence of their own eyes".

The "tidal wave" of refugees was itself "the clearest evidence" that war crimes were being committed, he said.

Robin Cook: "We will go on collating further evidence"

Mr Cook said: "We will not forgive and we will not forget" what he termed "Milosevic's final solution".

Speaking after the foreign secretary, Judge Arbour - the prosecutor for the International Tribunal for the Former Yugoslavia in the Hague - described the legal methods at her disposal as "very modest indeed".

She said the tribunal required state co-operation to function and thanked the UK Government for its efforts.

Blair pledge

Following her meeting with the foreign secretary on Tuesday Judge Arbour was due to meet UK Defence Secretary George Robertson.

Meanwhile, at a news conference at Nato headquarters in Belgium, UK Prime Minister Tony Blair reiterated the alliance's commitment to action against Yugloslavia.

Earlier, Mr Blair delivered a personal message of support to Nato's commanders via a video link.

In a message beamed to officers across Europe, he said: "I'd simply like to say to all of you, to thank all of you, for the work you are doing - not just the military action but the extraordinary humanitarian effort as well."

A UK Ministry of Defence spokesman said that RAF jets had been forced to abandon bombing raids on Monday night due to bad weather.