Defiant George Bush yesterday told critics of war in Iraq they were "lucky" to be free to protest when he makes the first full state visit to Britain by a US President.

Mr Bush arrives tomorrow with security services on their second highest state of alert following information that al Qaida supporters in north Africa could be planning an attack on the UK.

The alert is said to be unrelated to the President's visit but will further tighten security on what was already described as an "unprecedented" policing operation.

Five thousand officers and hundreds of security agents will protect the President during the series of protests planned to mark his stay, including a mass national rally on Thursday.

The White House says Mr Bush is "not fazed" by the prospect of mass demonstrations. And yesterday he told campaigners: "Aren't you lucky to be in a country that encourages people to speak their mind?"

Mr Bush insisted he had been right to invade Iraq and the fierce attacks on the US-led coalition would not stop reconstruction.

In an interview with BBC's Breakfast with Frost, he said the scale of the task had been anticipated. Evidence of weapons of mass destruction would be found, he pledged, and he defended US and UK intelligence as "sound".

He repeatedly praised key ally Tony Blair and said: "I am convinced that the decisions we made will make the world more peaceful and more free."

Former Foreign Secretary Robin Cook said the interview showed Mr Bush had not learned from what had "plainly" gone wrong in Iraq. "If President Bush does not learn the lessons there is that risk he will ask us to do it again in another country," he said.

Mr Bush will be confronted by protestors from around the country when he makes his expected visit to Mr Blair's Sedgefield constituency, in County Durham, on Friday.

Ricky Heaven, of the Stop the War Coalition, said the scale of the protest would depend on what security measures were in place.

He said: "We don't want him to come up here without letting him know how we feel, but it depends on what we're allowed to do.

"I would imagine they will be extremely heavy handed and aren't going to allow us to demonstrate freely."

The Reverend Martin King, the rector of Sedgefield, said he would take part in any peaceful demonstration. "This really is an awfully troubling time," he said.

Mr Blair admitted that Mr Bush's critics were "rubbing their hands at the scope for embarrassing him". But the PM said: "I believe passionately that there could not be a better moment for him to come to the UK than now.

"Nor a better opportunity for our two countries to re-affirm both our special relationship and our commitment to give the Iraqi people the chance for a better, more prosperous and peaceful future."

The family of Guisborough-born Christopher Maddison, of Scarborough - who was killed during a battle near Basra - are due to meet the President along with other relatives of servicemen who have died in the conflict.

His stepfather, Tony Maddison, said: "I'm beginning to feel Mr Blair has been a puppet, so I'm looking forward to meeting Bush, to ask, 'What are you doing to our Prime Minister?"

Mr Maddison said he believed the British were deceived over the war, and that the weapons of mass destruction argument was raised to "frighten" the country.

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