Saddam Hussein is getting rattled and his regime weakening as the military build-up in the Gulf continues, Tony Blair has said.

The UK prime minister made the claim during his twice-yearly grilling from the House of Commons Liaison Committee.

The comments came as preparations got under way to send another 26,000 UK troops to the Gulf, with America set to deploy an extra 37,000.

UK troops in the Gulf

Royal Navy Task Group has set sail Personnel include Royal Marines from 3 Commando Brigade Headquarters 1 (UK) Armoured Division Support from the Desert Rats 16 Air Assault Brigade 102 Logistics Brigade 120 Challenger tanks 150 Warrior armoured personnel carriers

Click here for map of UK military build-up

It also came just before an anti-war lobby of parliament that was attended by pop group Blur's frontman Damon Albarn.

Mr Blair told MPs it was "inevitable" that al-Qaeda would try to launch a terrorist attack on the UK.

In his two-and-a-half hour question session, Mr Blair said: "The one thing that is very obvious is that as a result of the military build-up and as a result of the determination to see this thing through, the regime in Iraq and Saddam are weakening.

"They are rattled, they are weakening, we are getting a massive amount of intelligence out of there now as to what is happening in Iraq, and that is why we have to keep up the pressure every inch of the way."

Anti-war protest

Anti-war Labour MP George Galloway suggested that was wishful thinking and that in fact a wave of nationalism was sweeping Iraq.

The Iraqi president meanwhile has insisted the troops amassing in the Gulf are not keeping him awake at night.

Blur star opposes war

There has always been a sense of unease about this war Damon Albarn

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Saddam told the official Iraqi News Agency: "I fall asleep as soon as I put my head on the pillow."

Meanwhile, anti-war campaigners gathered in Westminster to protest at the military build-up.

Parliament was lobbied by groups including Stop the War, CND and the Muslim Association, with hundreds mounting a vigil in Parliament Square.

In the light of the protests and following a Guardian/ICM poll suggesting shrinking public support for possible war, Mr Blair said: "I totally understand why public opinion is sceptical."

Stark omissions

But he was confident any action would come in circumstances people would find "acceptable and satisfactory because there is no other route available to us".

Later, Foreign Secretary Jack Straw told MPs there were "stark omissions" in Iraq's weapons declaration.

The Desert Rats... can seize ground, they can hold ground General Patrick Cordingley, former Desert Rats commander

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Mr Straw said: "For too long, Iraq has flouted international legal obligations to disarm and laughed in the face of the UN."

News of the latest troop deployment is the most significant step so far in the British military build-up.

Over coming days equipment will start to be moved to ports in Britain and Germany to be shipped out.

Troops should be in Kuwait by mid-February, but ministers stress no decisions about using them have been taken.