* Osh remains tense after ethnic violence
* U.N. concerned about security, Islamist radicalism
* Interim leader speaks to Clinton ahead of Blake’s visit
(Adds details, Amnesty)
By Dmitry Solovyov
SURATASH, Kyrgyzstan, June 17 (Reuters) - Makeshift camps on both sides of Kyrgyzstan’s border with Uzbekistan are home to 400,000 refugees uprooted by ethnic violence, the United Nations said on Thursday, and the area remains extremely tense.
Many refugees are running short of basic supplies and fear fresh attacks. In one camp, clay houses were crammed with dozens of refugees and many others are having to sleep rough.
At least 191 people have been killed since June 10 in south Kyrgyzstan in clashes between Uzbeks and Kyrgyz. The government says the death toll is several times higher.
In Osh, the epicentre of the clashes, people in Uzbek neighbourhoods have built barricades, in effect demarcation lines separating them from Kyrgyz parts of the city.
The army has set up checkpoints around Osh but its security presence is low. Groups of men armed with AK-47s patrolled the streets. It was unclear where their allegiance lay.
Several Uzbeks were attacked after crossing into the Kyrgyz side to visit a hospital, observers on the ground said.
"It’s extremely tense. It’s highly flammable. Uzbeks and Kyrgyz are completely separated," Ole Solvang, an observer from Human Rights Watch, said during a visit to Osh, the country’s second largest city which is close to the Uzbek border.
Home to U.S. and Russian air bases, Kyrgyzstan has been turbulent since a revolt in April toppled its president, Kurmanbek Bakiyev, and brought an interim government to power.
The new leadership, which has not been formally elected, is holding a referendum on June 27 on constitutional changes it says will make the country more democratic.
The government issued a decree saying it would cancel the referendum only if the entire country were in a state of emergency, or if a state of emergency were to be enforced in regions containing more than half of the total electorate.
It needs the vote to entrench its rule and has been broadcasting frequent television advertisements promoting the poll, but it said it could not guarantee the violence was over.
The United Nations High Commissioner for Refugees said in a statement some 300,000 refugees were massed on the Kyrgyz side, citing information provided by the interim government and non-governmental organisations on the ground.
A further 100,000 people have poured into Uzbekistan since last week, it said. Kyrgyzstan’s population is 5.3 million.
"Sporadic clashes have reportedly taken place around the town of Jalalabad and the situation there is tense," the UN refugee agency said in a statement. Jalalabad is close to the Uzbek border in south-western Kyrgyzstan.
In one camp, refugees queued for bread distributed from local stockpiles. Many of them were women and children, and some had weeping sores on their feet. They boiled and drank clay-coloured water drawn in buckets from a pool in the village.
"We no longer have any trust left for the Kyrgyz," Mavlyuda Abdrakhmanova, a 43-year-old woman, said. Many others were holed up in remote hide-outs with little food and water, locals said.
Humanitarian aid has been flown into the region from Russia, the United States and other powers. But observers on the ground said it was not reaching most camps and neighbourhoods on the Kyrgyz side because of security concerns.
Amnesty International called for an international inquiry.
"The ... interim government must react immediately to allegations of collusion of security forces and send a clear signal that any human rights violations will be prosecuted," it said. Officials were unavailable for comment late on Thursday.
STRATEGIC BUT VOLATILE
The UN said continued turmoil would offer a breeding ground for Islamist militancy in Central Asia, a region lying on a major drug trafficking route out of nearby Afghanistan.
Kyrgyzstan’s cash-strapped government operates a small and under-equipped army and it said the violence could re-ignite.
"We cannot say that everything has been contained and stopped," Alik Orozov, secretary of the Security Council, told reporters. "There are forces out there that have yet to be defeated. To explode the situation in (the capital) Bishkek you don’t need an army. A band of 15-20 militants (is enough)."
U.S. Secretary of State Hillary Clinton spoke to interim leader Roza Otunbayeva by telephone on Thursday to discuss the conflict, the interim government said in a statement.
Assistant Secretary of State Robert Blake, the top U.S. official for Central Asia, is due to visit Bishkek on Friday.
Urgent international support is needed in Kyrgyzstan and to assist Uzbekistan to care for the flood of refugees who have fled across the border, said the OSCE High Commissioner on National Minorities, Knut Vollebaek. (For more on Kyrgyzstan click on [ID:nLDE65A145]) (Additional reporting by Olga Dzyubenko in Bishkek and Robin Paxton, Maria Golovnina in Almaty; Writing by Maria Golovnina; editing by Robert Woodward)