Russia sent at least 150 paratroopers to Kyrgyzstan on Sunday to protect its military facilities as ethnic clashes spread in the Central Asian state, bringing the death toll from days of fighting to 113.
Ethnic Uzbeks in a besieged neighbourhood of Osh, Kyrgyzstan's second-largest city, said gangs were carrying out "genocide," burning residents out of their homes and shooting them as they fled. Witnesses saw bodies lying on the streets.
"God help us! They are killing Uzbeks like animals. Almost the whole city is in flames," said Dilmurad Ishanov, an ethnic Uzbek human rights worker in Osh.
Rights activists said the authorities were failing to stop the violence, and occasionally joining in.
"Residents are calling us and saying soldiers are firing at them. There's an order to shoot the marauders, but they aren't shooting them," said ex-parliamentary deputy Alisher Sabirov, a peacekeeping volunteer in Osh.
Takhir Maksitov of human rights group Citizens Against Corruption said: "This is genocide."
Renewed turmoil in Kyrgyzstan, a former Soviet republic, has fuelled concern in Russia, the United States and neighbour China. Washington uses an air base at Manas in the north of the country, about 300 kilometres from Osh, to supply its forces in Afghanistan.
Several units of paratroopers arrived on Sunday to protect servicemen and families at Russia's Kant airbase in the north of the country, a Kremlin spokesman said. A Defence Ministry spokesman said 150 armed paratroopers had been sent, while ITAR-TASS news agency, citing ministry sources, said at least 300 were dispatched.
The interim government in Kyrgyzstan, which took power in April after a popular revolt toppled president Kurmanbek Bakiyev, has appealed for Russian help to quell the riots in the south.
Led by Roza Otunbayeva, the interim government has sent a volunteer force to the south and granted shoot-to-kill powers to its security forces in response to the deadly riots, which began in Osh late on Thursday before spreading to Jalalabad.
UN Secretary-General Ban Ki-moon said he was alarmed by the scale of the clashes and ordered a special envoy to travel to the Kyrgyz capital Bishkek, his office said in a statement.
The Red Cross said the humanitarian situation in southern Kyrgyzstan is "becoming critical."
"We are getting reports of severe brutality, with an intent to kill," it said in a statement.
The increase in violence has killed more people than the riots that accompanied the overthrow of Mr. Bakiyev. Ms. Otunbayeva, whose government has only limited control over the south, has accused supporters of Mr. Bakiyev of stoking ethnic conflict.
Mr. Bakiyev issued a statement from exile in Belarus, describing claims he was behind the clashes as "shameless lies."
The Health Ministry said 113 people had been killed - 92 in Osh and 21 in Jalalabad - and 1,405 were wounded. At least five policemen have been killed, the Interior Ministry said.
"Kyrgyz groups are driving in and setting homes on fire. When the people run out, they shoot at them," Andrea Berg, Central Asia researcher at Human Rights Watch, said by telephone from Osh.
Kyrgyzstan and Uzbekistan intertwine in the Fergana Valley. While Uzbeks make up 14.5 per cent of the Kyrgyz population, the two groups are roughly equal in the Osh and Jalalabad regions.
The latest clashes are the worst ethnic violence in southern Kyrgyzstan since 1990, when then-Kremlin leader Mikhail Gorbachev sent Soviet troops into Osh after hundreds of people were killed in a dispute that started over land ownership.
Meanwhile, thousands of women and children have crossed the border into Uzbekistan.