The UN High Commissioner for Refugees says at least 10,000 people have been driven from their homes since the start of the Ukraine crisis.
Most of them are ethnic Tatar Muslims who fled Crimea after it voted in a referendum on 16 March to separate from Ukraine.
The Tatars said they were fearful of persecution.
However, most of them have stayed in Ukraine rather than seeking refugee status abroad. Half of them went to central Ukraine and about a quarter to the west of the country.
Government forces are fighting pro-Moscow separatists in the eastern Ukraine.