Tony Blair has admitted that tough issues will be on the agenda when he meets George W Bush next week.

The prime minister told MPs that steel tariffs, the fate of Britons detained at Guantanamo Bay and the crisis in Iraq will all be discussed during the president's visit.

The commitment came after Liberal Democrat leader Charles Kennedy warned the prime minister that he had a responsibility to raise the "indefensible" situation of British citizens being held in Camp Delta.

Blair's pledge to be frank with the president came as Number 10 sought to talk down the row over the security arrangements for the visit.

Downing Street has insisted that the Metropolitan Police has been given full operational control of next week's state visit by President Bush.

The comments came amid reports that the White House has ordered an exclusion zone to be created around George W Bush during his three-day visit.

Number 10 denied claims that ministers have intervened to ensure that all protesters are kept well away from the first family.

It also refused to say whether the president's armed protection officers have been granted immunity should they be forced to fire on protesters who breach the security cordon.

A spokesman for the prime minister said London's police chiefs had "the experience, the judgement and the right" to make the final security decisions about next week's event.

"In a democracy there is a balance to be struck between the right to demonstrate and the right of people - including visitors - to go about their normal business," he said.

"In a democracy we give the job of striking that balance to the police and it will be their job to strike that balance as they have done in the past.

"Judgments about how to control demonstrations and where demonstrators can and cannot stand will be operational matters for the police."

The Metropolitan Police has already cancelled all leave in order to prepare for a £4 million security operation in Central London.

Chief constable Sir John Stevens said road closures would be announced at "the last minute" for security reasons.

"We will keep those to a minimum, we must make sure London continues to operate as normally," he said.

The controversy surrounding President Bush's state visit grew after Downing Street admitted large scale protests were inevitable.

Washington-based officials claim an exclusion zone, which could create gridlock in the Capital, is essential for security reasons.

But they have been accused of attempting to shield the president from the negative publicity the protests would generate.

Whilst the London mayor wants the city centre to remain as open as possible, American security chiefs want to close the area around Buckingham Palace and the Mall.

Some 100,000 anti-war protesters have vowed to take to the streets during the three day visit by the president.

Downing Street admitted on Tuesday that protesters would target the event but called on those with "strong views" to recognise the important relationship between Britain and the US.

Foreign secretary Jack Straw said he hoped people understood the importance of Britain's relationship with the US.

"What I hope will come from this visit and consideration about these visits is a mature reflection on our relationship with the US and Europe. America is our largest trading partner by far," he said.

"Huge numbers of jobs on both sides of the Atlantic depend on that relationship."

London's anti-war mayor Ken Livingstone has warned, however, that any exclusion zone would create chaos for the people of London.

"The ideas of some American security advisers that perhaps we should shut the whole of central London for three days, ignoring the economic consequences of that, I don't think that's got a chance at all," he said.

Anti-war protesters yesterday vowed to breach any no-go area and expect tens of thousands to join the "Stop Bush" protest.

Some fear that the flashpoint may come when the president attends a ceremony at Westminster Abbey next Thursday.

"Stop the War" protesters say they will resist any moves to block them marching down Whitehall and past parliament.

"It is an outrage that the most unwelcome guest this country has ever received will be given the freedom of the streets, while a movement that represents majority opinion is denied the right to protest in the area which is the heart of government,'' said the group's convener, Lindsey German.

Liberal Democrat mayoral candidate Simon Hughes said described the visit as "ill-judged, ill-conceived and inappropriate".

He called for security to remain in the hands of the Metropolitan Police and for protestors to be allowed to make their case.

"The president and his entourage must also be aware of the protests that occur and must not be shielded from the opinion of the British public," said Hughes.

"Whatever our long standing and good links with America, the war in Iraq has generated huge concern amongst the British people, and President Bush should get to know about these first hand."

The Met updated the media on the policing of the visit at a special briefing late on Wednesday.

Further details of the president's schedule, which is likely to include a banquet at Buckingham Palace and a visit to the prime minister's Sedgefield constituency, will be released to the media next Monday.