South Korean activists have hurled firebombs into a US military base in protest against last week's acquittal of two American soldiers who ran over and killed two South Korean girls.

The attack follows a string of protests over the soldiers' court cases, which demonstrators have denounced as a sham.

The two girls were hit by a mine-clearing vehicle

Monday's protest at Camp Gray, a small US support post in south-western Seoul, caused no injuries or property damage, the US military said.

A US statement said it respected the activists' right to protest but condemned the attack.

"We will not condone violent demonstrations which could cause injuries and damage to facilities or those acts which infringe upon the rights and freedoms of others," the statement said.

In a separate demonstration, a small group of protesters gathered outside the US embassy in downtown Seoul, shouting anti-US slogans.

Legal dispute

The US soldiers' case have fanned anti-American sentiment in South Korea, where 37,000 US troops are stationed to counter threats from the Communist North.

Since the soldiers' acquittals, the country's political parties have called for a revision of the US-South Korean military accord to allow Seoul to exercise jurisdiction over criminal cases involving US soldiers.

At the moment, the US has the right to try its own soldiers.

The South Korean government had asked for jurisdiction in the case of Sergeant Mark Walker and Sergeant Fernando Nino, but the US refused.

They were both cleared of negligent homicide.

US apologies

Shim Mi-sun and Shin Hyo-son, 14, were walking to a friend's birthday party on 13 June when they were mowed down by the US vehicle, which was taking part in a training exercise on the outskirts of Seoul.

The defence for Sergeant Nino argued that he alerted Sergeant Walker to the presence of the girls. The driver says he never heard the warning, because of an apparently defective communications system.

US senior officials, including Secretary of State Colin Powell, have repeatedly apologised over the case.

Following Friday's acquittal, army commander Lieutenant General Charles Campbell repeated the US military's apology over the deaths, but defended its legal system.

"I want again to express my sincere apology and deepest sympathy to the families of Shim Mi-Son and Shin Hyon-Sun. This was a tragic loss of life and we are deeply sorry," he said in a statement.

"Taken together, the verdicts in the two trials that were rendered by two different impartial panels indicate that what occurred was a tragic accident without criminal culpability."