Action against Iraq will be in weeks not months, George Bush said last night.

After meeting Prime Minister Tony Blair, the US President said they were both agreed on the matter.

Earlier, Mr Bush said he backed the use of nuclear missiles in retaliation against an attack with weapons of mass destruction.

He signed a document stating that America reserved the right to respond with "overwhelming force - including potentially nuclear weapons" if Saddam Hussein launched an assault with chemical or biological arms.

Speaking at a joint White House press conference, President Bush repeated that both men were agreed: "This matter will come to a head in a matter of weeks, not months."

Mr Blair praised his host's leadership in the fight against what he said were the linked threats of terrorism and weapons of mass destruction.

However, he has repeatedly said he would prefer action sanctioned by a second United Nations Security Council resolution.

"What is essential is that in every respect, in every way that we can, we mobilise international support and the international community in order to make sure these twin threats the world faces are dealt with," Mr Blair said last night.

There was no talk of deadlines as some people had predicted.

Instead, Mr Bush said that Saddam was not disarming and, as a result, was a danger to the world.

Mr Blair reiterated that resolution 1441 stated that Saddam had a final opportunity to disarm and that he had to co-operate fully with the UN weapons inspectors.

"But as Dr (Hans) Blix said earlier this week in his report to the Security Council, he's not doing that and, therefore, what's important is that the international community comes together and makes it absolutely clear that this is unacceptable," he told reporters.

"The reason, I believe, that it will do that is precisely because in the original resolution 1441, we made it clear that failure to disarm would lead to serious consequences."