The number of Ukrainians who have fled the country since Russia's invasion two months ago is approaching 5.2 million, the UN refugee agency said Sunday.

The total figure of 5,186,744 is an increase of 23,058 over Saturday's data, the UNHCR said.

More than 1,151,000 Ukrainians have left during April so far, compared with 3.4 million in the month of March alone.

The latest figures come as Ukrainians mark Orthodox Easter Sunday.

"For the people of Ukraine, and those forced to flee the country, it will be another day of fear, anguish, loss and separation from loved ones, as war continues to rage without mercy," the UN High Commissioner for Refugees Filippo Grandi wrote on Twitter.

"May strength and courage be with them."

The UN's International Organization for Migration (IOM) said an additional 218,000 citizens of third countries -- largely students and migrant workers -- have also escaped to neighbouring countries since the February 24 invasion.

Women and children account for 90 percent of those who have fled abroad, with men aged 18 to 60 eligible for military call-up unable to leave.

Beyond the refugees, the IOM estimates more than 7.7 million people have been displaced within Ukraine.

Almost two-thirds of Ukrainian children have had to flee their homes, including those who remain in the country.

Before the invasion, Ukraine had a population of 37 million in the regions under government control, excluding Russia-annexed Crimea and the pro-Russian separatist-controlled regions in the east.

Here is a breakdown of how many Ukrainian refugees have fled to neighbouring countries, according to UNHCR:

Nearly six out of 10 Ukrainian refugees -- 2,899,713 so far -- have crossed into Poland.

Many of them have travelled on to other states in Europe's Schengen open-borders zone.

The latest figures come as Ukrainians mark Orthodox Easter Sunday in wartime
The latest figures come as Ukrainians mark Orthodox Easter Sunday in wartime AFP / Dimitar DILKOFF

Meanwhile, more than 800,000 people have crossed from Poland into Ukraine, Polish border guards said.

Before the war, Poland was home to around 1.5 million Ukrainians, chiefly migrant workers.

A total of 774,074 Ukrainians have entered the EU member state as of April 22, 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.

Another 578,255 refugees have sought shelter in Russia, according to data last updated on April 21.

In addition, 105,000 people crossed into Russia from the separatist-held pro-Russian regions of Donetsk and Lugansk in eastern Ukraine between February 18 and 23.

A total of 489,754 Ukrainians have entered Hungary.

The Moldovan border is the closest to the major port city of Odessa. A total of 433,214 Ukrainians have crossed into the non-EU state, one of the poorest in Europe. Most have moved on.

A total of 354,329 people have crossed Ukraine's shortest border into Slovakia.

Another 24,084 refugees made it north to Russia's close ally Belarus as of April 21.