A local human rights activist has claimed that as many as 500 people may have been killed when Uzbek troops fired on thousands of protesters and clashed with rebels in the town of Andizhan yesterday.
"The total number of deaths could reach 500 people from both sides," the local head of Uzbek human rights group Appeal, told Reutersfrom the eastern town.
He said he based his estimates on conversations with witnesses and his own observations.
Earlier Uzbek President Islam Karimov has blamed Islamic militants for violence in the east of the country in which troops fired on protesters and rebels, killing dozens of people.
In his first statement on yesterday's violence in Andizhan, Mr Karimov denied any order had been given to troops to open fire, saying the outlawed Islamist group Hizb ut-Tahrir was responsible for the deaths which followed the rebel seizure of a state building.
"I know that you want to know who gave the order to fire at them ... No one ordered (troops) to fire at them," a visibly angry Mr Karimov told a news conference in the capital Tashkent.
Mr Karimov, in power since before mainly Muslim Uzbekistan gained independence from the Soviet Union in 1991, said 10 police and troops had been killed and 100 wounded. He said there was even higher number of rebel casualties, but made no mention of civilian dead or wounded.
The violence in Uzbekistan follows unrest in neighbouring Kyrgyzstan where violent protests - which started in the city of Osh just across the border from Andizhan - led to the ousting of President Askar Akayev.
Mr Karimov said the rebels had hoped the Kyrgyzstan upheaval would help them to foment trouble. In the past 18 months, there have also been "bloodless revolutions" in two other ex-Soviet republics, Ukraine and Georgia, both of which installed Western-leaning leaders. Central Asia's hardline leaders have reacted by clamping down further on dissent.
Amid fears of more bloodshed, security services gave foreign journalists 30 minutes to leave the city, saying they could not vouch for their safety in the town in the east of the Ferghana Valley, seen as a hotbed of Muslim extremists by the government.
The anti-government Hizb ut-Tahrir denied starting the violence. The pan-Islamic group has been blamed by Mr Karimov for several past attacks, but it says it is non-violent. Mr Karimov said Hizb ut-Tahrir was behind explosions last July that killed four people at the US and Israeli embassies and the prosecutor's office in Tashkent, and suicide bombings that killed 50 people a year ago.
The protesters, some calling for Mr Karimov to stand down, gathered yesterday after rebels freed prison inmates, including 23 businessmen charged with religious extremism. The rebels then seized the building and took about 10 police hostage.
There were also signs of trouble spreading through the densely populated Ferghana Valley, home to nearly a quarter of all Uzbeks, as 500 refugees fled across the closed border to Kyrgyzstan, a Kyrgyzstan border guard spokeswoman said.
Uzbekistan, a Central Asian country bordering Afghanistan, offered the United States use of a military airbase after the September 11 attacks and has become an ally in Washington's war on terrorism. The country is one of the world's leading cotton exporters, is a gold producer, and has some oil and gas reserves.