Swedish Foreign Minister Carl Bildt has said he is worried about the rising numbers of refugees moving from Crimea and eastern regions to other parts of Ukraine because of the crisis in the country.

"Worried by rising numbers of displaced persons in Ukraine. UNHCR [Office of the United Nations High Commissioner for Refugees] talks of 10,000 already," he wrote on Twitter, commenting on a report posted by the UN Refugee Agency on Tuesday.

As earlier reported, the UNHCR on Tuesday said the tension in Ukraine had displaced an estimated 10,000 civilians and added that the number of people affected was continuing to rise.

Displacement in Ukraine started before the March referendum in Crimea and has been rising gradually since. Among the affected population are people who have been displaced twice - first from Crimea, and then again from the eastern part of the country. Most of those displaced are ethnic Tatars, although local authorities have also reported a recent increase in registrations of ethnic Ukrainians, Russians and mixed families. At least a third of the displaced people are children.