Nearly 4.25 million Ukrainians have fled the country during Russia's invasion, while a further 7.1 million are thought be internally displaced within Ukraine, the United Nations said Tuesday.
UNHCR, the UN refugee agency, said 4,244,595 Ukrainians had fled across the country's borders since the war began on February 24 -- a figure up 29,548 since Monday.
Meanwhile the UN's International Organization for Migration estimated that 7.1 million internally displaced people (IDPs) had fled their homes but were still in Ukraine.
The IOM says that in addition to Ukrainian refugees, more than 206,000 non-Ukrainians living, studying or working in the country have also left.
This means that in total, more than a quarter of the population have been forced to flee.
Before the Russian invasion, Ukraine had a population of 37 million in the regions under government control, excluding Russia-annexed Crimea and the pro-Russian separatist regions in the east.
"The cessation of hostilities in Ukraine is of utmost importance, to allow for humanitarian access to all affected populations," the IOM said.
Women and children account for 90 percent of those who have left Ukraine, with men aged 18 to 60 eligible for military call-up and unable to leave.
Speaking via video-link Tuesday to a conference of European mayors in Geneva organised by the UN, Kyiv mayor Vitali Klitschko decried a "genocide" in his country.
"If someone thinks the war is far away, and this war doesn't touch you, it's a mistake. This war can touch everyone in Europe," he said.
Here is a breakdown of how many Ukrainian refugees have fled to neighbouring countries, according to UNHCR:
Nearly six out of 10 Ukrainian refugees -- 2,469,657 so far -- have crossed into Poland, according to the UN tally. Polish border guards said the number had reached 2.5 million on Tuesday.
Many people who go to Ukraine's immediate western neighbours travel on to other states in Europe's Schengen open-borders zone.
The Polish border guards said that since the war began, 471,000 people have left Poland for Ukraine.
Before the crisis, Poland was already home to around 1.5 million Ukrainians, chiefly migrant workers.
A total of 648,410 Ukrainians have entered the EU member state, including a large number who crossed over from Moldova, wedged between Romania and Ukraine.
The vast majority are thought to have gone on to other countries.
The Moldovan border is the closest to the major port city of Odessa, which was hit by air strikes Sunday. Some 396,448 Ukrainians have crossed into the non-EU state, one of the poorest in Europe.
Most of those who have entered the former Soviet republic of 2.6 million people have moved on.
A total of 394,728 Ukrainians have entered Hungary.
Some 350,632 refugees had sought shelter in Russia as of March 29.
In addition, 113,000 people crossed into Russia from the separatist-held pro-Russian regions of Donetsk and Lugansk in eastern Ukraine between February 21 and 23.
A total of 301,405 people have crossed Ukraine's shortest border into Slovakia, according to latest figures up to Monday.
Another 16,274 refugees had made it north to Russia's close ally Belarus.