The State Department said it was “deeply disturbed” by the reported massacre in Andijan. “We certainly condemn the indiscriminate use of force against unarmed civilians and deeply regret any loss of life,” said its spokesman Richard Boucher.

But despite President Bush’s pledge to make the “end of tyranny” the hallmark of his second term, US officials tip toed around direct criticism of the regime of President Karimov, who has given the US a priceless “footprint” in Central Asia by allowing the Pentagon to open an airbase in his country.

Condoleezza Rice, the US Secretary of State, offered no direct censure of Uzbekistan as she flew back to Washington after her surprise visit to Iraq. She merely called on Mr Karimov to adopt political reforms to head off future outbreaks of violence. “This is a country that needs, in a sense, pressure valves that come from a more open political system,” she said of the Central Asian republic.

She said Washington’s main concern was to prevent further violence, but made no public appeal to Mr Karimov. Her tempered response put the US at odds with Britain, where for the second day running Jack Straw, the Foreign Secretary, issued a firm denunciation of the violence. “This plainly cannot be justified,” he said, adding that he was “very concerned”.

Mr Straw refused to accept Mr Karimov’s explanation for the violence at face value. The Uzbek leader, whose authoritarian rule began when the republic won its freedom from the former Soviet Union 14 years ago, blamed it on Islamic extremists.

Mr Straw said it was impossible to verify “in any precise way” Mr Karimov’s version of events because the Uzbek authorities have refused to allow diplomats, aid workers or reporters to visit Andijan. Mr Straw demanded such access immediately.

The violence was threatening to spread across eastern Uzbekistan yesterday amid reports of protests and fighting in towns and villages near Andijan, where Uzbek troops fired on anti-government demonstrators on Friday after armed rebels took over government buildings and freed prisoners from jail. Witnesses said that hundreds were killed.

Tensions were mounting on the border with Kyrgyzstan as hundreds of Uzbeks, including some rebels, tried to cross the closed frontier to escape Uzbekistan’s worst violence since independence in 1991.

Police in the town of Pakhtabad, about 18 miles northeast of Andijan, said they had repelled a group of armed men who tried to force their way across the border to Kyrgyzstan. Saidjahon Zaynabitdinov, head of the local human rights group, Appeal, said that troops had killed about 200 demonstrators in Pakhtabad on Saturday, although there was no independent confirmation. Kyrgyz authorities said they had also turned back 150 Uzbek refugees trying to cross the border illegally near the Uzbek village of Ayim and gave warning that they would deport others.

At least eight government soldiers and three civilians were killed in violence at the border town of Teshiktosh on Sunday as hundreds of Uzbeks fled into Kyrgyzstan, witnesses said.

The UN High Commissioner for Refugees (UNHCR) said that 560 people, mainly men, had crossed the border into Kyrgyzstan as refugees since unrest began. “There is a great deal of worry on the ground,” a spokesman said. “The Kyrgyz authorities are preparing for the worst.”

In another border community, Korasuv, 5,000 people went on a rampage on Saturday, beating up local officials and forcing them to restore a bridge across a river that marks the border with Kyrgyzstan.

“Every day, people are becoming more and more angry because of the lawlessness of the army. People think that those who left for Kyrgyzstan will return with arms. They are afraid,” Muzafarmizo Iskhakov, chairman of the human rights group, Ezgulik, told The Times.

President Karimov has blamed the revolt on the banned Islamic group Hizb ut-Tahrir, which calls for the setting-up of an Islamic state in Central Asia. His Government denies that troops opened fire on protesters. But several witnesses say that troops fired into the crowd, killing 500 people.

Opposition campaigners rallied in the Uzbek capital, Tashkent, yesterday in the first public show of anger there since the violence in Andijan. Tashpulat Yuldashev, a political analyst, said: “It was a black day in Uzbek history. We are ashamed. We dissidents have been long afraid of standing up to express our discontent. But this time we can’t stay silent.”

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