The rally coincided with South Korea's independence anniversary

Demonstrators threw stones at police near the US embassy after shredding a giant replica of an American flag.

Police responded by firing water cannons into the crowd.

South Korea is set to send 3,000 troops to Iraq this month becoming the third largest contributor to the multi-national force, after the US and UK.

President Roh Moo-hyun cautioned against "blind" anti-Americanism.

Washington ties

At the march on Sunday, the demonstrators urged President Roh to cancel the troop deployment to Iraq, or step down.

"We are not foolish enough to let the government dispatch troops to Iraq... We are not that ignorant," they sang, according to the Associated Press news agency.

Police used water cannons to hold back the protesters

Seoul has argued the deployment of its soldiers in Iraq will aid reconstruction and strengthen ties with Washington.

South Korea already has 670 personnel in northern Iraq, where they are believed to be preparing a base for the incoming soldiers.

President Roh criticised anti-American protests on the anniversary of the country's liberation from Japanese forces in the World War Two.

"This attitude seems to reflect the thinking that the United States is responsible for all the past, present and future problems of [South Korea]," he said.

The president also re-iterated his commitment to the pursuit of normal relations with thei communist neighbour, North Korea.

But protesters say their government's close ties with the US are hindering the detente with Pyongyang.