LONDON, Oct 17: Tens of thousands of demonstrators took to the streets of central London Sunday to protest against the Iraq war as Prime Minister Tony Blair struggled to shake off fierce criticism of the invasion back home.

Organisers said that between 65,000 and 75,000 protesters had taken to the streets for the peaceful march, which began at Russell Square, close to the British museum. Police put the figure at between 15,000 and 20,000.

The Stop The War Coalition organized the march. Protesters from around the world clutched banners and blew whistles as they marched towards Trafalgar Square, where a mass rally was to take place.

"Troops out," screamed one of many placards being waved by protesters. "Blair must go," said another.

Sunday's march was the latest in a series of demonstrations organised by the Stop The War Coalition before and after the US-led invasion, backed by Britain, of Iraq in March 2003.

The march was arranged Sunday to coincide with the end to the three-day European Social Forum held in London. It comes also after a stormy week for Blair, who was accused in parliament last Wednesday of misrepresenting intelligence on Iraq to make the case for war.

The brother of Kenneth Bigley, the British hostage recently executed by his captors in Iraq, urged people to turn out in force for Sunday's march.

"For Ken's sake and for the sake of everyone in Iraq I ask you to make your feelings known to our government, to protest and to join the demonstration," Paul Bigley was quoted as saying by the Press Association, Britain's domestic news agency. "The more people raise their voices, the safer we will all be."

Sunday's march came after 25,000 protesters marched through London in March on the first anniversary of the Iraq invasion.

On that occasion, two demonstrators scaled Big Ben, the landmark clock tower of the Houses of Parliament, at dawn and unfurled a banner that read: "Time for the truth."

Last November, up to 200,000 people protested in Trafalgar Square when President George W. Bush was in London.-AFP