Thousands of demonstrators have made their way through London as part of a huge protest against President Bush.

The second full day of the US leader's state visit to Britain has been marked by a march through Westminster to Trafalgar Square.

Ahead of the march, Tony Blair urged the protestors to listen to his case.

He said it was "extraordinary" that people could oppose the removal of the Taliban and the toppling of Saddam Hussein.

"Listen to our case as well. We listen. That's what a democratic case should be about," he said.

President Bush said people had a right to speak out in a free society.

And he dismissed claims that he was hated by the British people.

"I don't think they do. All I know is that the people in Baghdad weren't allowed to do this until recent history. Freedom is a wonderful thing," he told journalists.

The Stop the War Coalition insisted on a route that will take the protest along Whitehall while Bush is meeting with the prime minister in Downing Street.

A dispute over the path of the march was only resolved on Monday when the Metropolitan Police acceded to the request.

Up to 100,000 anti-war activists were expected to take part but estimates of the turnout varied.

The Metropolitan Police claimed around 1,000 people, some of whom who are intent on violence, travelled from Europe to take part in the protest.

Crowds outside Buckingham Palace on Wednesday were lower than expected for the president's official welcome on Wednesday.

But following February's million-strong pre-war march, the Met has cancelled all police leave in order to deal with the demonstration.

In his keynote speech on Wednesday the president that he welcomed the right British citizens have to express their opinion.

"I notice the tradition of free speech exercised with enthusiasm is alive and well here in London," he joked. "We have that at home too. They now have that right in Baghdad as well."

However Stop the War spokesperson Lindsey German said the march would "show the huge strength of opposition to the president's visit".

"[The] people of America and people of Britain don't support the war in Iraq," she added.

"Liberal democracies should listen to their people. It's time to bring the troops home."

Joining today's march will be Labour MP Jeremy Corbyn and rebel former Labour MP George Galloway.

Islington North MP Corbyn said the marchers would be voicing their anger over a range of issues.

"The march will focus on Iraq but it will also be joined by people who are concerned about the prisoners in Guantanamo Bay and the Kyoto," he said.

"It's not anti-American; it's going to be led by Americans in fact."

Liberal Democrat MEP Sarah Ludford , who will also be marching, echoed a similar sentiment.

"This protest is very personal: it's not anti-American but anti-'Bush and Blair'," she said.

"President Bush is right to say that the American and British peoples have an 'alliance of values' but it is precisely because these values are being betrayed by the 'alliance of Bush and Blair' that protest is generated.

"Why is there so little action to build security through toughness not only on terrorism but on the causes of terrorism like poverty and environmental degradation?"