By Caroline Gluck BBC Seoul correspondent

President George W Bush has expressed regret over the deaths of two South Korean schoolgirls who were run over by a US military vehicle in June.

The message was announced at a press conference held by the US ambassador in Seoul, Thomas Hubbard, and the head of US forces in Korea, General Leon LaPorte.

Ambassador Hubbard conveyed the president's apology

Last week the driver and commander of the military vehicle involved in the accident were cleared by a court martial of negligent homicide.

But the case has provoked widespread protests.

President Bush's statement may go some way towards assuaging public anger over this case.

In his message, conveyed through the US ambassador to South Korea, the president offered his apologies to the families of the schoolgirls, the government and the people of South Korea.

"He asked me to express, and here I quote, his 'sadness and regret over this tragic incident' and to reiterate the United States' commitment to work closely with the Republic of Korea to help prevent such accidents from occurring in the future," said Thomas Hubbard.

In recent months there have been a string of apologies from US diplomats and military officials following the deaths of two teenage girls. But the public mood here is still heated.

'Whitewash'

The protests have become increasingly violent, following last week's acquittal of the two sergeants involved in the accident.

The two girls were hit by a mine-clearing vehicle

This week, radical students threw Molotov cocktails inside one military base, and broke into another base after cutting a perimeter fence.

Protesters said the court martial was a whitewash, and demanded that the soldiers stand trial in a South Korean court - a call rejected by the US military.

The government in Seoul seems to have been surprised by the violence of the reactions. On Tuesday President Kim ordered a crackdown on the illegal protests.

The real fear is that the case could cause serious long-term damage to military and diplomatic ties between South Korea and the United States.