Britain and the US reserve the right to go it alone in Iraq, the foreign secretary said on Tuesday.

Speaking following the publication of a draft United Nations resolution, Jack Straw said all options remained open.

Warning that the UN had to deliver, he said that London and Washington would not duck difficult decisions.

Quizzed about what would happen if the security council rejected the resolution, he said: "If it is not passed, what the British government has said is that we reserve the right to make decisions in the light of those circumstances."

The move came as the government's critics stepped up their campaign against a conflict.

The Liberal Democrat foreign affairs spokesman, Michael Moore, told the House of Commons that the UK's draft resolution was "premature and divisive".

And senior trade unionist Bill Morris earlier said there were still "a number of unanswered questions" about Tony Blair's approach.

"I don't see how we got from the containment policy to the imminence of war," he said.

Pop star George Michael warned that the prime minister was "more arrogant" than Margaret Thatcher.

The attack came as it emerged that Tony Blair will take to youth TV as part of his on-going PR battle.

Downing Street said the prime minister will take part in a one-hour forum on MTV to debate with young people from across Europe "Is War the Answer?"

The programme will go out on March 7 and will be seen by an audience of around 300 million young people across Europe, the US, Asia, the Middle East and Australia.

"This forum will not be a vehicle for any political message; instead we wish to offer an open and unscripted dialogue between Tony Blair and young people in Europe," said the station's president Brent Hansen.

As the government seeks to win popular support for a war, intensive discussions are on-going in New York.

Ministers are letting it be known that the next fortnight will be a major test of the United Nations.

Ahead of Blair's statement to MPs, the foreign secretary said the UN security council had dragged its heels for too long.

"This is an important moment for the United Nations. The security council knows there has been endless time and that has been matched by endless prevarication exploiting equivocation in the international community," said Straw.

"The United Nations can only operate if it accepts its responsibilities. We believe that words must mean what they say."

The Conservatives have urged the government to take a tough line against the French government.

Speaking in the Commons, shadow foreign secretary Michael Ancram urged Straw to condemn the "arrogant and bullying behaviour" of the French president, Jacques Chirac.