Tony Blair has raised fresh expectations that he is on the verge of committing ground troops to Yugoslavia to finish off the war with Slobodan Milosevic.

In a series of question time exchanges, Tory leader William Hague signalled a switch of policy by confirming he was now in favour of the use of ground forces.

The change came as he joined with Liberal Democrat leader Paddy Ashdown to warn the prime minister that time was running out for the alliance in Kosovo.

If the allies are to build up a credible ground force in time to act before winter closes in and effectively shuts off the option, the decision needs to be taken within the next couple of weeks.

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Mr Blair said he was aware of the time constraints and insisted he was ready to act.

But, with the US Congress having banned President Bill Clinton from sending in American ground troops, there are fears the threat may appear a hollow one.

Pass the parcel

Some cynics even suggested that the leading Nato nations are now involved in a game of "pass the parcel" to ensure they are not blamed for the failure of the campaign through a lack of will.

The exchanges between Tony Blair and William Hague at Prime Minister's Questions

Mr Blair again stressed that, with the arrival of summer, he expected the air campaign to succeed.

Better weather conditions and more daylight hours will give the bombers a significant boost.

But he carefully stoked up speculation that, with opposition support, he was now closer than ever to committing ground forces.

William Hague: "Decisions on ground troops needed"

The exchanges also marked a significant cooling of the row which erupted between Foreign Secretary Robin Cook and his shadow, Michael Howard, earlier in the week.

Mr Howard's robust attack on Nato for the bombing of the Chinese embassy in Belgrade led to fears that the cross-party alliance over the war was falling apart.

The two leaders appeared more united during question time, but Mr Hague still demanded clear explanations from the government.

He was greeted with jeers from the Labour benches as he said: "We support the government in their aims of getting the Serbs out of Kosovo and getting the refugees home and we, like you, wish to see the air strikes succeed."

Deploy troops

But he continued: "Nato, despite all our hopes for the air strikes, may soon confront a difficult choice - either to accept a compromise which you have already rightly said you would regard a failure or to pursue a different military course that will achieve these objectives.

"If we wish to assemble and deploy troops to allow the refugees to return home before the winter, Nato needs to make any decision on ground troops in the very near future."

Mr Blair thanked him for his support and added: "As far as I'm concerned, there will be no compromise on Nato's demands.