Tony Blair's hopes of a United Nations mandate for war appeared slimmer than ever last night.

First, the French, Russians and Germans insisted they would not let a resolution for military action pass - and then the UN's chief weapons inspector said there had been "proactive" cooperation by the Iraqis

Mr Blair had told MPs earlier that he was "confident" of securing the second resolution, which polls suggest is vital if he is to retain the support of the public and prevent a devastating split in the Labour Party.

But within hours, the foreign ministers of France and Russia used a joint news conference with the Germans to give their strongest signal yet that they may use their Security Council vetoes to block it.

Hans Blix's statement about Iraqi cooperation with his inspectors in recent months gave a further boost to the anti-war camp.

Although he was careful to state that he would not want to make a request for more time for the inspections simply on that basis, his comments will fuel claims that the inspections are beginning to work and are worth pursuing.

Mr Blair has previously said that Britain would prefer a fresh UN resolution mandate before committing troops to war, but would not be held back by a single "unreasonable" veto in the Security Council.

It is unclear what his position would be if two, or even three, permanent members combined to block the resolution, tabled jointly by the US, the UK and Spain.

The Prime Minister confirmed yesterday that the draft resolution would be put to a vote if Dr Blix reports on Friday that Saddam Hussein is still failing to comply fully with the demands of the international community.

"If he fails fully to comply, there should be a vote in the UN and I very much hope the UN supports the position it set out in resolution 1441 last November, which called upon him for full, unconditional and immediate compliance," he told MPs during Prime Minister's Questions.

"It is plain at the present time he is not in such compliance."

Mr Blair's spokesman acknowledged that Moscow had "a different perspective" about how to secure Saddam's disarmament, but stressed its agreement on the need to disarm him.

Yesterday, Russian foreign minister Igor Ivanov stood alongside his French and German counterparts, Dominique de Villepin and Joschka Fischer, in Paris, as Mr de Villepin said: "We will not allow the passage of a planned resolution which would authorise the use of force.

"Russia and France as permanent Security Council members will fully assume all their responsibilities."

Asked if France was ready to use its veto, Mr de Villepin replied: "We are totally on the same line as Russia."