Thousands of British peace campaigners took to the streets of London on Saturday to protest against the continued war in Afghanistan, as NATO members' heads of state met in Portugal to discuss their future Afghan strategy.

Organizers said that more than 10,000 demonstrators gathered in Hyde Park in central London for a two-kilometer march to Trafalgar Square, where they heard speeches criticizing the continued war in Afghanistan.

The march set off peacefully at 1 p.m., with colorful banners flying and many protesters holding placards calling for troops out of Afghanistan, as well as other causes like "Solidarity with Palestine."

The march was organized by "The Stop the War Coalition," "The Campaign for Nuclear Disarmament," and "The British Muslim Initiative." "The Stop the War Coalition" came into being in September 2001, less than a fortnight after the 9/11 attacks in the United States.

Andrew Burgin, a press spokesman for "The Stop the War Coalition," said the demonstration had been very effective, and had attracted lots of people under the age of 20.

He added: "The demonstration was a good demonstration. We want the government to bring the troops home from Afghanistan. We are very pleased with the demonstration -- It was a very young one."

Dominic O'Dwyer, from "The Stop the War Coalition" in the west of England city of Bristol said: "I don't feel I can stand by and do nothing while our troops are being brought home in coffins, and while they are being so badly maimed for what I see as a futile and pointless war. I also think it is an unjust war. Clearly we are not winning there anyway, our own commander of our armed forces has admitted as much. And I don't see any reason for delaying in getting our troops out now. Those are the reasons I have come on the demonstration today."

He added: "I think NATO will go ahead and do what it wants to, but I have got to go ahead and exercise my democratic right to protest and hope that it will be somehow instrumental in bringing about the earliest possible exit from Afghanistan by all NATO forces."

NATO nation heads of state met Friday night and Saturday in Lisbon, capital of Portugal, in a summit which NATO secretary general Anders Fogh Rasmussen described as highly significant for the military alliance's future. Leaders are expected to agree to a strategy for withdrawal of soldiers from Afghanistan that could see all combat troops out of the country by the end of 2014.