According to the agency, the number of those who'd left totaled 6,029,705 people as of May 11, 90 percent of them women or children.
Many of the millions who've fled have gone to neighboring countries, with the highest number traveling to EU member Poland.
Among those who fled Ukraine are also Ukrainian nationals with dual citizenship, the agency said.
An additional 105,000 people moved to the Russian Federation from the Donetsk and Luhansk regions between 18 and 23 February.
Eight million more Ukrainians have been internally displaced by Russian aggression. (ILKHA)