It is believed such a policy is under-pinned by the fear that violence in the province could mean it is the next Bosnia.

Military intervention inside Kosovo is out of the question because the United Nations Security Council would not allow intervention inside a member state.

But an option could be to develop a ring of troops around the territory to try to prevent the fighting spreading.

The Prime Minister is reported to have said: "The only question that matter is whether you are prepared to use force. And we have to be."

Balkans flare-up

Following Thursday's meeting in Downing Street, Mr Blair is said to have told his closest ministers: "Reports indicate a level of butchery that risks escalating into another Bosnia."

The Prime Minister believes the lessons of Bosnia meant it was better to decide "whether and when to intervene rather than be dragged in", Downing Street sources said.

With more than 250 people reported to have been killed in clashes with the Serb forces in the past three months, Mr Blair's is keen to toughen sanctions against President Slobodan Milosevic's regime in Belgrade.

Mr Blair has been studying reports of the worsening situation in the province and, sources said, he has been "struck by the level of agreement in favour of a tough line" among other European leaders, whom he has been visiting on a tour of capitals in the run-up to the Council of Minister's meeting in Cardiff this month.

Foreign Secretary Robin Cook will be urging EU agreement for a ban on new investment in Serbia, an extension to existing sanctions, when Foreign Ministers meet on Monday.