Uzbek security forces have sealed off the centre of Andijan city, where many people were shot dead on Friday.
Andijan residents have been trying to find and identify dead relatives
Troops are on the streets, hunting the leaders of anti-government protests and roads into Andijan are closed.
It is still not known how many people died when soldiers opened fire on demonstrators in the city square. Estimates vary from dozens to hundreds.
UK Foreign Secretary Jack Straw told the BBC there had been "a clear abuse of human rights" in Uzbekistan.
Mr Straw said the situation was "serious" and called for more transparency from the Uzbek government.
The city of Andijan was quiet on Sunday, with most people staying at home.
Relatives are frantically searching morgues, hospitals and the city's streets for those who died.
"I have been looking for two days for the bodies of my brothers," Bakhadyr Yergachyov told the AFP news agency.
Most populous central Asian former Soviet republic, home to 26m people
Ruled since independence in 1991 by autocrat Islam Karimov
Accused by human rights groups of serious abuses, including torture
Rocked by violence in capital Tashkent in 2004
Government says radical Islamic groups behind violence
"I know that they had gone to the square to participate in the demonstrations."
Armed guards dressed in tracksuits are patrolling the grounds of the hospitals and outsiders, like journalists, are not allowed in.
There have been a few funerals, but many people said the authorities have not released the bodies of all those killed.
Correspondents in Andijan report seeing up to 50 bodies on the streets, though some local witnesses said they had seen as many as 300.
The Associated Press cited a doctor saying 500 bodies had been laid out in a school for identification.
Official figures are much lower.
The BBC's Monica Whitlock said without any independent humanitarian agencies operating in the region, the true figure may never emerge.
Many people are distressed that the state-controlled media have broadcast only minimal news of what happened.
They do not know if the rest of Uzbekistan or the outside world knows or cares, our correspondent says.
There are almost no reporters in the city and those with cameras have been ordered out.
Roads into Andijan have been blocked.
Hundreds of people, including women and children, are said to have crossed the nearby border with Kyrgyzstan to a refugee camp on the other side.
At the border, Uzbek authorities were nowhere to be seen, following clashes with locals on Saturday, the BBC's Ian MacWilliam reported.
In the border town of Karasu, he said, local people rebuilt two bridges that had been destroyed by Uzbek forces, and said they intended to resume the cross-border trade they had relied on for years.
Uzbek President Islam Karimov blamed the unrest in Andijan on what he described as criminals and Islamic radicals linked to the banned Hizb ut-Tahrir movement, who wanted to overthrow the government.
Mr Karimov, an ally of both Washington and Moscow's war on terror, has taken a tough line on security since a spate of suicide bombings last year, blamed on Islamic extremists.
But critics say he is using the threat of extremism as a cover to crush dissent.
Many of those who had demonstrated in Andijan said it was poverty and unemployment - rather than political or religious demands - that brought them onto the streets.