More than 400 Uzbek refugees who fled into neighboring Kyrgyzstan following a violent government crackdown in May will be flown out of the country Thursday and resettled in third countries, the U.N. refugee agency said Wednesday.

"A humanitarian evacuation is underway," Carlos Zaccagnini, head of the Kyrgyz office of the U.N. High Commissioner for Refugees, said in a telephone interview from the capital, Bishkek. He said that 305 refugees had already been airlifted to the capital and that the entire group would probably be ready to depart from the Bishkek airport Thursday.

The Uzbek refugees, who had been living in a tent city in western Kyrgyzstan near the Uzbek border, have been the focus of intense diplomatic pressure on Kyrgyzstan's young government, which came to power after a popular revolt in March. Kyrgyzstan's president-elect, Kurmanbek Bakiyev, won by a landslide in a July 10 vote.

Uzbekistan has demanded that some of the refugees be forcibly returned, but the United Nations, Western governments and human rights groups have insisted that they are entitled to refugee status.

With most of the refugees now scheduled to leave Kyrgyzstan, attention has turned to 29 Uzbeks who were imprisoned by Kyrgyz authorities in the southern city of Osh on suspicion that they had criminal backgrounds. Uzbek authorities have insisted on the return of at least 12 of the 29 who they say are criminals who were among hundreds of detainees broken out of prison on May 13 as a day of protests began in Andijan, a city in eastern Uzbekistan.

The U.N. agency has classified the 12 men as refugees, Astrid van Genderen Stort, a spokeswoman for UNHCR in Geneva, said in a phone interview. The agency insists that their deportation would be a violation of Kyrgyzstan's obligations under international law, she added.

Human Rights Watch said two Uzbek vehicles entered the prison Wednesday evening, but U.N. officials said the vehicles later left without any prisoners.

"We are very worried about this development," Stort said. "We have raised this at the highest levels with the Kyrgyz government and they said we should not be worried, that there was no way the 12 will be handed over to the Uzbeks."

But the Russian news agency Interfax quoted Kyrgyz prosecutors as saying that the 12 most wanted detainees could still be handed over to the Uzbeks.

The cases of four other Uzbeks are still under review, Stort said, and they will not be able to leave the country Thursday. Kyrgyz officials said those four are suspected of having committed serious crimes in Uzbekistan.

U.N. officials insist that refugees returned to Uzbekistan face a risk of being tortured or summarily executed.

Most of the refugees to be resettled will be flown to a temporary transit point Thursday and interviewed by officials from countries willing to accept them. U.N. officials declined to identify the third countries involved in the resettlement process. Romanian officials confirmed that they had held discussions with UNHCR about temporarily hosting the refugees.

A spokesman for Canada's Immigration Ministry said that "as part of a larger international operation with other resettlement countries, including the United States," Canada had agreed to resettle up to 50 Uzbek refugees, the Reuters news agency reported. No other details were available.

The crisis in Andijan began May 12 when as many as 100 men attacked government facilities. The following day, they stormed a prison and freed prisoners, including 23 businessmen on trial on charges of religious extremism. As many as 10,000 people had joined a protest against the government in the city's central square when Uzbek security forces opened fire, killing hundreds of people, according to human rights groups and witnesses, including the refugees in Kyrgyzstan.

The Uzbek government has said that 173 people were killed, most of them Islamic radicals. The government has rejected calls for an independent international inquiry into the events.

An Uzbek officer leaves a prison where 29 Uzbeks are being held in the Kyrgyz city of Osh. The U.N. refugee agency is seeking their release.