"I would hope we would have over 100,000 people demonstrating," said Kate Hudson, vice-chairwoman of the Campaign for Nuclear Disarmament (CND), part of the umbrella group Stop the War Coalition.

The coalition had been forecasting as many as 400,000 protesters would descend on the centre of the capital at 12:00 p.m. local time (1100 GMT) for the walk past Downing Street, parliament, and on to Hyde Park.

"We know that there are hundreds and hundreds of coaches coming from around the country from the different local groups that have been organising over the past couple of weeks," Hudson told AFP.

Some organisers of the anti-war movement have been accused of "hijacking" the strong public feeling against military action in Iraq for their own ends.

"They are hard-line Marxists whose agenda is very different to those who are doing the demonstrating," said Labour MP David Winnick.

But Hudson said the march was a response to the fact that the war was still continuing, people were being killed and illegal weapons such as cluster bombs were still in the field.

"We also take the view that this, of course, an illegal war. We'd like our troops to be brought home now," she said.

Protesters were starting off from two separate assembly points in central London before meeting in Parliament Square, outside the House of Commons, where a minute's silence was to be be held.

Flowers, wreaths and cards were being laid outside Downing Street before the protesters moved to Hyde Park for a rally addressed by speakers including four MPs from Britain's ruling Labour party.

Saturday's march through London will be the third held in the capital in recent weeks over the Iraqi conflict, and was planned to coincide with a massive protest in Washington.

On February 15, more than one million people took to the streets of London to protest the then looming war on Baghdad in what police said was the largest demonstration in the British capital.

On March 22, two days after the start of hostilities, between 200,000 and 700,000 people protested in the British capital.

SPACE.WIRE