Tony Blair is already convening a small group of senior ministers who will become Britain's War Cabinet once troops are committed.

Seven ministers - including party chairman John Reid and chancellor Gordon Brown - have already begun meeting each morning in Downing Street.

The group also includes the deputy prime minister, the foreign secretary, the defence secretary and the international development secretary.

It is also thought that senior defence chiefs and key Downing Street advisers are also attending the daily meetings.

As the government braces itself for the start of military action, the man who will put British troops into armed conflict has said he is ready to "execute the order" at any moment.

Air Marshal Brian Burridge said his forces were ready for the imminent attack on Iraq.

With the clock ticking towards George W Bush's Thursday deadline, British and US forces were on a high state of alert.

The Royal Air Force officer - who will give the signal to attack on the orders of Downing Street - said he was "very much hoping that right now Saddam is looking for his passport".

"He hasn't used it much since 1968. That's the option and if he doesn't take it then we will be at war," he told PA News.

Speaking at the UK nerve centre in the US central command base in Qatar, the commander said: "We will get on and do it and we are both physically - in the preparation of equipment - and mentally attuned for war."

Huge columns of armoured vehicles were moving into position south of the Iraqi border today, the vanguard of a force of around 300,000.

Soldiers close to the border were put on a high state of alert in case of an Iraqi pre-emptive strike prior to the Bush deadline.

Colonel Chris Vernon, at British Army headquarters near the Iraq border, said that younger soldiers facing combat for the first time were "understandably apprehensive about what they may be about to face".

"But they will get on and do what they have to do if required," he insisted.

"There is a high state of readiness among all the men I have encountered and they are now all primed and ready to go.

"Some units have already moved to forward assembly areas on the front line and are now just awaiting orders."