Fighting between ethnic Kyrgyz and Uzbeks in southern Kyrgyzstan has left at least 200 people dead, officials say. However the country's interim leader says the death toll could be as high as 2,000.
The UN says some 400,000 people have been displaced, with thousands of Uzbeks fleeing across the border to Uzbekistan.
The BBC looks at the background to the events.
What triggered the violence?
Tensions have been high in the area since President Kurmanbek Bakiyev was ousted in an uprising on 7 April 2010. His stronghold in the south became the centre of instability.
Among the Kyrgyz population, pro-Bakiyev elements organised resistance to the interim government by seizing government offices and taking officials hostage. The sizeable Uzbek community displayed sympathy to the new government in Bishkek.
As Roza Otunbayeva, the interim president, struggled to control the south, well-established criminal elements and drug dealers exploited the power vacuum. The communal violence was sparked by a clash between Kyrgyz and Uzbek gangs in the southern city of Osh.
It soon turned into street fighting among youths. Fuelled by rumours of atrocities on either side, angry mobs from other towns and villages arrived in Osh, forcing large numbers of ethnic Uzbeks to flee.
Are there longer-term causes?
Osh is situated in a fertile plain known as the Fergana Valley. The valley was divided among three Soviet republics.
After the fall of the Soviet Union, these became independent republics, with minority populations and enclaves in separate countries with international border crossings.
The last serious outbreak of ethnic disturbance was put down by Soviet troops in 1990. Since then, the Kyrgyz part of the Fergana Valley has become a magnet for increasing trade with neighbouring countries, a thriving market for cheap Chinese goods and the centre of illicit drugs from Afghanistan on their way to the world markets.
Successive Kyrgyz governments failed to deal with growing corruption and crime there. Collapsing infrastructure and widespread poverty contributed to deep public resentment.
The Fergana Valley is an area of largely devout Muslims as well as the recruiting ground for Islamist movements.
The minority Uzbek population makes up 15% of Kyrgyzstan's five million people. In Osh, Uzbeks are in the minority. In some areas of the Fergana Valley, they outnumber the Kyrgyz population.
Many local Kyrgyz fear the Uzbeks want to grab Kyrgyz lands and join Uzbekistan. This seems to be a significant factor in the violence of recent weeks.
Does the interim government have much control?
The provisional government of Roza Otunbayeva has struggled to keep control of the southern region, where pro-Bakiyev elements continue to have considerable influence.
With the outbreak of ethnic violence, the government declared emergency rule in the south but failed to establish law and order.
Ms Otunbayeva's appeal to Russia to send troops was widely seen as evidence of the government's inability to deal with the situation.
The interim government has sent a volunteer force to the south and granted shoot-to-kill powers to its security forces.
This was criticised by human rights organisations, which called on the Kyrgyz government forces to follow the basic international principles on the use of force and firearms.
Human Rights Watch, whose representative was caught up in troubles in Osh, repeated a call for a UN-mandated force to assist the Kyrgyz government in providing protection and stopping ethnic violence engulfing Osh and spreading to other cities in southern Kyrgyzstan.
EU foreign affairs chief Baroness Catherine Ashton called for moves to form a stable government, echoing worries that the Kyrgyz interim government was failing to provide security for its population.
Have supporters of the ousted president stoked the violence?
Kyrgyzstan's interim government has accused supporters of the ousted leader Kurmanbek Bakiyev of fuelling conflict to undermine its efforts to hold a referendum on 27 June on a new constitution.
Former president Bakiyev has denied involvement and called for the regional security bloc to send forces to Kyrgyzstan.
There were unconfirmed reports of Mr Bakiyev's son, Maxim Bakiyev, and his brothers trying to undermine the new government.
Even if there is an element of Bakiyev supporters stoking trouble, the mass killings and fighting are too indiscriminate to be explained by this factor alone, say analysts.
The UN High Commissioner for Human Rights, Navi Pillay, says these have been ethnic clashes.
What has been the impact of the violence on Uzbekistan?
Kyrgyzstan's instability is having a wider regional impact in Central Asia. It borders China, Kazakhstan, Tajikistan and Uzbekistan.
It is Uzbekistan that has been drawn into the crisis first. For the first time in its modern history, Uzbekistan opened its borders to refugees, as thousands of ethnic Uzbeks sought sanctuary there.
Makeshift refugee camps have sprung up along the Uzbek-Kyrgyz border, and Uzbekistan fears its capacity to help will soon run out. In response the UN is calling a flash fundraising appeal to help provide food and shelter.
Meanwhile, hundreds of refugees are streaming back into Kyrgyzstan, many to find their homes destroyed.
In the short term, the chaos and destruction witnessed in Kyrgyzstan could well strengthen the hands of the authoritarian leaders in the region.
What has been Russia's response?
At the height of the violence, interim leader Roza Otunbayeva appealed to the Russia government to intervene and restore order in the south.
Russia, which has 150 soldiers stationed in Kyrgyzstan, said it was not prepared to send troops as it was "an internal conflict", but would send humanitarian aid to the violence-hit region.
The Collective Security Treaty Organisation, chaired by the Russian president, has approved an aid plan, which includes sending armoured vehicles and helicopters that will be used in maintaining security in the country's south.
Russians seem to be favouring the option of participating in a peacekeeping mission rather than acting alone.
Russia fears that it could get pulled into a quagmire. Mr Medvedev called the situation in Kyrgyzstan "intolerable" and said it constituted a regional emergency.