The Kyrgyz government is facing international calls for a probe into ethnic violence that the country's interim leader says has killed up to 2,000 people in the south.

U.S. Assistant Secretary of State Robert Blake urged the provisional government to launch an investigation into what caused the clashes between ethnic Kyrgyz and Uzbeks and ensure accountability for the "perpetrators."  

Blake made the comments Friday after visiting with some of the 400,000 refugees who have crossed into Uzbekistan or massed near the Uzbek border.

The U.N. Human Rights Council also called for a "full and transparent" probe in a resolution adopted Friday.

Interim Kyrgyz leader Roza Otunbayeva on Friday made her first visit to the region since the riots began June 10 in the southern cities of Osh and Jalalabad.

The interim leader told reporters in Osh Friday that her government will do everything it can to rebuild the city so people can return home.

The United Nations estimates that as many as 1 million people have been affected by the unrest.

Human Rights Watch and the International Crisis Group sent a joint letter to the U.N. Security Council Friday, calling for the deployment of a "stabilization mission" to provide security for the distribution of aid and refugees wanting to return home.

The groups say the ethnic violence in Osh and Jalalabad has resulted in killings, rapes, beatings and widespread burning and looting of homes.  

Human Rights Watch and the International Crisis Group also say there are a growing number of reports that Kyrgyz military and other security personnel "not only failed to stop the violence, but in some cases may have been active participants."

U.S. Secretary of State Hillary Clinton said Friday (in Washington) that such allegations have to be taken seriously, but that the international focus should be on supporting interim authorities in getting humanitarian aid to the displaced.

A U.N. refugee agency spokesman says two planes carrying 80 tons of relief are due to arrive in Osh Saturday and Sunday.  A sixth relief flight into Uzbekistan is expected to land in Andijan later Friday, with 240 tons of relief supplies delivered this week.

The Russian defense ministry said Friday it was considering a Kyrgyz request to dispatch Russian troops to protect strategic sites in the Central Asian nation.

The interim government has blamed deposed President Kurmanbek Bakiyev and his supporters of fomenting the violence.  Mr. Bakiyev was ousted in an April 7 uprising that killed 85 people.  His son, Maxim, was arrested in London earlier this week and is seeking asylum in Britain.  The interim government accuses him of fraud.

Some information for this report was provided by AFP, AP and Reuters.