The International War Crimes Tribunal for former Yugoslavia, based in The Hague, issued an arrest warrant for the Yugoslav President after the court's investigators ammassed a wealth of evidence of terrible crimes against humanity from refugees now in Albania and Macedonia.
The tribunal's chief prosecutor, Louise Arbour, is expected to announce the indictment today but officials insisted it had already been signed.
The court is not an arm of Nato and has no power to bring the Serb leader to justice.
But the indictment still marks a crucial step in the Kosovo conflict as in effect it bars the West from negotiating a diplomatic end to the war while he is in power. And it will strengthen the hand of Nato hawks arguing for a ground invasion of Kosovo. "I don't see how anyone can negotate with Milosevic on behalf of the West now," one European diplomat said.
The report came as Britain - the leading hawk in Nato - said it would send another 12,000 fighting troops to the region.
By putting highly trained combat units on stand-by to join 45,000 extra troops in Nato's K-For ground force, including the Paras and the Gurkhas, Tony Blair sent out the clearest signal so far that Britain and Nato are prepared to fight their way into Kosovo to return the refugees to their homes.
It is also an admission that the air campaign alone is not enough to force President Milosevic into submission.
Britain's offer to send 12,000 troops in addition to the 5,400 already deployed in Macedonia is intended to take pressure off President Bill Clinton in the face of failing public support in the United States for American troops to be used on the ground in Kosovo.
The Secretary of State for Defence, George Robertson, denied assembling an invasion force, saying that the extra troops would be needed to rebuild Kosovo's infrastructure after the war. But military experts were quick to note that Britain is sending a hard-hitting force more suited to fighting than to rebuilding houses.
Three infantry battalion groups were put on reduced notice to move - the first battalion of the Royal Irish Rangers, the first battalion of The Parachute Regiment and the first battalion of the Royal Gurkha Rifles. In addition, 3 Commando Brigade was put on standby with the Amphibious Ready Group, including HMS Ocean, Fearless and auxiliary vessels.
Mr Robertson described it as a "major and momentous undertaking". Paddy Ashdown, the Liberal Democrat leader, who has been calling for ground forces to be used, said the troops were "frontline arms", and the Prime Minister said it was a "significant and right move". Mr Blair appeared to accept that he was moving from peace-keeping to peace-making in Kosovo.
"We shall make sure there is sufficient force so that the refugees can be allowed back home properly," he said. "It is important that we make sure ... that we have sufficient ground forces to do the job."
Nato decided on Tuesday that the planned total of 28,000 for K-For was not enough. The number deployed in the region could rise to between 55,000 and 60,000.
Mr Robertson's Commons statement came amid mounting evidence that Nato could secure widespread support for a ground force to enter Kosovo in a "non-permissive environment" if the air campaign and diplomacy fail to dislodge Mr Milosovic's men.
As the Foreign Secretary, Robin Cook, toured three European capitals yesterday it emerged that the Germans would not block the entry of Nato forces into Kosovo ahead of a peace agreement, in spite of Chancellor Schroder's earlier statement that a land campaign was "unthinkable".
British officials believe Italy might take the same line. Lamberto Dini, the Italian Foreign Minister, stressed after his meeting with Mr Cook the importance of the diplomatic process, but he agreed that it had to be backed by firm military action.Reuse content