More than 5,00,000 people have left Ukraine since the start of Russia's military operation and about 1,60,000 have become internally displaced, UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Martin Griffiths told the UN Security Council on Monday.

"According to the latest figures from the UN Refugee Agency, more than half a million people have already crossed the international borders, mostly towards Poland. An additional 1,60,000 have been internally displaced. This is likely a significant underestimation as the numbers are changing by the hour," Griffiths said.