The number of inhabitants in the Ukrainian region of Donetsk has shrunk from 1.67 million to about 340,000 as a result of the war in the country.
Governor Pavlo Kirilenko reported those numbers on Wednesday, more than three months after the start of the Russian invasion.
Russian troops in eastern Ukraine, where the Donetsk and Luhansk regions form the Donbas, are trying to advance further. After the capture of the port city of Mariupol in southern Donetsk, the cities of Kramatorsk and Sloyansk have become the main targets of the Russian army, Kirilenko said.
Millions of Ukrainians have fled because of the war. Of the 6.8 million people who have left Ukraine since February 24, 2.9 million have travelled through neighbouring countries to other countries in Europe.
Figures from the United Nations also show that more than 2.2 million refugees have returned to their home countries, in some cases for a short period of time.