The UN High Commissioner for Refugees says millions Ukrainians have been forced to flee their homes in the wake of Russia's invasion.

Filippo Grandi tweeted on Sunday that roughly 10 million refugees have fled abroad or been displaced inside the country.

The office of the UNHCR says that as of Saturday the number of Ukrainians who fled abroad had topped 3.38 million. It added that nearly two-thirds of the refugees, about 2.05 million, had evacuated to Poland and about 180,000 were sheltering in Russia.

Meanwhile the International Organization for Migration says that as of Wednesday, the number of displaced people inside Ukraine was estimated to be 6.48 million.