MOSCOW – Thousands of refugees fled to the border in an attempt to escape violent clashes in Uzbekistan yesterday as witnesses reported that eight Uzbek soldiers and three Islamic militants died. As many as 500 people were killed when government forces opened fire on demonstrators in the eastern city of Andijan on Friday.

A teenage boy who had witnessed the attack on Friday told Reuters that troops had opened fire on a crowd of 3,000 protesters and shot them down “like rabbits.” The protests erupted after armed rebels stormed a jail, freed prisoners accused of Islamic extremism, and occupied the local government headquarters.

There was still no official death toll yesterday, but both a doctor and a human rights campaigner in the area put the number of dead at 500. Thousands more were injured.

It was the worst violence in Uzbekistan since the country gained independence following the breakup of the Soviet Union in 1991. The protesters had demanded the resignation of Uzbekistan’s authoritarian president, Islam Karimov, who has ruled the nation of 26 million since independence. Uzbekistan’s state-controlled television gave no comprehensive account of the events in Andijan, and authorities shut down access to foreign TV networks, including CNN, the British Broadcasting Corp., and Russian networks.

[Eight Uzbek soldiers and three Islamic militants died in a clash near the Kyrgyz border yesterday, witnesses said, in spreading violence that further threatened the country’s stability, the Associated Press reported.

Reports of 11 dead yesterday in fighting in the border village of Tefektosh could not be confirmed, but blood stains were visible on the streets. One villager said eight government soldiers were killed. Another said three civilians also died. Other accounts said more than 500 people, including militants, crossed into Kyrgyzstan after the clash.

In Korasuv, another border community, the village was strewn with the charred remains of police cars yesterday, and documents from torched government offices were strewn on the streets.]

Mr. Karimov accuses the rebels of being Islamic extremists in league with international terrorist organizations. But while many agree that extremist groups have made inroads in Uzbekistan, some critics accuse Mr. Karimov of using the threat of Islamic terrorism to crack down on democratic opposition. Peaceful revolutions in former Soviet republics such as Georgia, Ukraine, and Kyrgyzstan, which neighbors Uzbekistan, have overturned autocratic leaders in recent years.

On Saturday, Mr. Karimov said troops were given no order to fire in Andijan. He blamed the violence on rebels belonging to the outlawed Islamist group Hizb ut-Tahrir, which denied involvement.

The violence is sure to worry the Bush administration, which has hailed Mr. Karimov as an ally in the war on terror. Uzbekistan hosts a large American airbase used for operations in neighboring Afghanistan.

The British Foreign Secretary, Jack Straw, called on Uzbekistan to allow the Red Cross and foreign observers into the country to verify casualty reports. He said he was “extremely concerned by reports that Uzbek troops opened fire on demonstrators.”

The Uzbek government reacted angrily in a statement yesterday.

“How did Mr. Jack Straw know that law enforcement agencies started shooting demonstrators if nothing of this kind ever happened?” the statement read. “Mr. Straw first should better have analyzed what happened and only then make such loud statements.”

Russia, in contrast, supported Mr. Karimov, with its foreign minister, Sergei Lavrov, saying the unrest had been a provocation “staged by groups similar to the Taliban,” according to the Interfax news agency. He said international organizations, including the United Nations and the Commonwealth of Independent States, which brings together former Soviet countries, should investigate the situation.

The violence was triggered by the trial in Andijan of 23 businessmen accused of belonging to a group called Akramiya that the government says is a front for Islamic extremists. The group denies connections with extremists and says it only supports peaceful resistance to autocratic rule. It is named after its founder, Akram Yuldashev, an Islamic dissident who was sentenced to 17 years in prison in 1999 for allegedly calling for Mr. Karimov’s overthrow. He denies the charge.

Witnesses said yesterday that there were no more protesters at the square that was the center of violence in Andijan. Two days after the uprising, blood and body parts reportedly remained on the pavements, streets, and gutters of the town of 300,000.

The Interfax news agency reported that Uzbek troops had fired on civilians trying to flee to the border with Kyrgyzstan. It quoted one of the refugees as saying: “There have been 1,000 people in the column I was moving in towards the border. … Uzbek troops shot at us several times although we shouted to them that we are civilians. … There were wounded and as far as I know four people were killed.”

Other sources reported that up to 4,000 people were fleeing to the border with Kyrgyzstan, which is home to many ethnic Uzbeks, particularly in the fertile Ferghana Valley. Representatives of the U.N. High Commission on Refugees were at the border yesterday and confirmed that 560 Uzbeks had arrived, most of them men, and that 18 of them were wounded. The UNHCR said in a statement that it had received assurances from Kyrgyzstan that its border would stay “open to those in need of international protection.”