A U.S. official is urging Kyrgyzstan's interim government to ensure safe conditions for the return of hundreds of thousands of refugees uprooted by last week's ethnic violence.

Assistant secretary of state Robert Blake said ethnic Uzbek refugees need "an atmosphere of trust and security" so that they can return to their homes, "to live in safety and harmony with their Kyrgyz neighbours."

Blake made the comment Saturday after he arrived in the Kyrgyz capital, Bishkek. Earlier, he toured several refugee camps in Uzbekistan.

About 400,000 people who are part of the country's ethnic minority have fled their homes and are staying at makeshift camps on both sides of the border with Uzbekistan, according to the UN High Commission for Refugees.

CBC's Alexandra Szacka, reporting from southern Kyrgyzstan, said many of those who were internally displaced are afraid for their lives, living behind barriers and roadblocks.

In a separate development, prosecutors in Kyrgyzstan have charged a human rights activist with inciting ethnic hatred for accusing the military of complicity in the violence.

Azimzhan Askarov, head of the Air rights group, was detained Tuesday near the southern city of Jalal-Abad, his colleagues said Saturday. Askarov had filmed some of the violence last Sunday.

The country's rights ombudsman, Tursunbek Akun, has insisted the charges were fabricated.

On Friday, Kyrgyzstan's interim president, Roza Otunbayeva, said ethnic clashes in the country's south, led mainly by Kyrgyz against Uzbeks, may have killed as many as 2,000 people.

Kyrgyzstan's opposition leaders formed a new government on April 8, unseating an unpopular president after a brief uprising.

Kyrgyz authorities have said the recent southern violence was sparked by associates of ex-president Kurmanbek Bakiyev, who was toppled amid accusations of corruption.

The UN has said the unrest appeared orchestrated, but has stopped short of assigning blame.

With files from The Associated Press