More than a quarter of a million people have fled ethnic fighting in southern Kyrgyzstan, the UN refugee agency says.
The UNHCR is mounting an emergency airlift of supplies for an estimated 75,000 ethnic Uzbeks who have fled to neighbouring Uzbekistan.
At least 170 people have died in rioting which began in the cities of Osh and Jalalabad.
Meanwhile, Maxim Bakiyev, son of ousted Kyrgyz President Kurmanbek Bakiyev, is reportedly being held in the UK.
The BBC understands he flew to Farnborough airport, England, in a private plane on Sunday and immediately claimed asylum.
He was moved to a police facility where he will be held while the asylum request is being considered.
The interim Kyrgyzstan government accuses him of spending millions of dollars to finance the riots and has officially asked Britain to extradite him.
The administration in the Kyrgyz capital Bishkek said on Tuesday that a national referendum on constitutional reform will go ahead on 27 June, despite the violence.
It has also dropped its request for the outside world to send a peacekeeping force to the Central Asian country, saying violence is waning. Russia has said it will not send troops to the country.
The UNHCR said the first of six cargo planes is scheduled to fly from Dubai to Andijan airport in Uzbekistan early on Wednesday carrying 800 lightweight tents.
The following five flights will be loaded with blankets, sleeping mats, kitchen sets and plastic sheeting for emergency shelters.
The agency says it is planning a separate airlift and the deployment of an emergency team to Kyrgyzstan.
About 200,000 people have been displaced inside the country, while another 75,000 have fled to Uzbekistan, according to the UN.
A UNHCR statement described the situation in Osh and Jalalabad as "difficult with sporadic fighting and attacks on civilians, including women and children".
"We fear that unless peace and order are restored swiftly more people could be displaced," it said.
The UN is also concerned that reports of rapes and killings could provoke ethnic violence in neighbouring countries.
UN spokesman Rupert Colville told the BBC that ethnic minorities in Tajikistan and Uzbekistan, along with other minorities in Kyrgyzstan, were at risk.
The police chief in the Osh region says reports of rapes and brutal killings could be true. Speaking to the BBC, he said the number of dead was likely to rise because many deaths had not been registered.
Former President Kurmanbek Bakiyev was toppled in a popular uprising in April.
The interim government that replaced him has accused Mr Bakiyev's family of instigating the violence to halt the 27 June referendum on a new constitution.
Uzbeks have mostly backed the interim government, while many Kyrgyz in the south have supported Mr Bakiyev, now in self-imposed exile in Belarus. He has denied any ties to the violence.
The interim government hopes the referendum will approve reforms that will pave the way for parliamentary-style elections in October.
Interim leader Roza Otunbayeva told a news conference: "We will fight to the last to ensure that the referendum takes place."
The UN and European Union had urged Kyrgyzstan not to allow the unrest to derail the referendum and elections.
At the weekend, Ms Otunbayeva appealed to Russian President Dmitry Medvedev to send military forces to Kyrgyzstan, saying that the situation in the south of the country was out of control.
But on Tuesday she told reporters: "There is not a need to send peacekeeping forces. We hope to deal with this situation with our own forces."
The clashes are the worst ethnic violence to hit southern Kyrgyzstan since 1990, when several hundred people were killed. Kyrgyzstan was then part of the Soviet Union, which sent in troops to quell the unrest.
Uzbek refugees say that armoured vehicles in Osh drove through streets in Uzbek neighbourhoods, shooting at civilians and clearing the way for gangs following behind.
Ethnic Uzbeks make up about 15% of Kyrgyzstan's 5.5 million people.
Central Asia's patchwork of ethnic groups competing for wealth and resources in countries controlled by their rivals has been described by UN officials as a "tinder-box".