GENEVA - More than half a million people have fled Ukraine since Russia invaded Thursday.
"More than 500,000 refugees have now fled from Ukraine into neighbouring countries," UN refugee chief Filippo Grandi said in a tweet around midday Monday.
The United Nations' refugee agency, UNHCR, had previously said it is planning to deal with up to four million if the situation worsens.
But the European Union's crisis management commissioner says the figure could reach seven million.
- Poland -
A UNHCR breakdown issued when the total tally was slightly below 500,000 showed that more than 280,000 people have already fled Ukraine into Poland.
Poland's border guards said Sunday that 90 percent of those arriving were being put up by friends or relations, but that reception centers were also being set up close to the frontier.
Poland was already home to 1.5 million Ukrainians before Russia invaded.
Across the country people are mobilizing with offers of accommodation, money, clothes and work for the new arrivals.
- Romania -
The UN refugee agency also found that over 32,500 Ukrainians had crossed into Romania since Thursday.
Bucharest meanwhile had said Sunday that around 47,000 Ukrainians had crossed into the country since Thursday, but that 22,000 had already gone on to other countries.
Most are passing through Siret in the north of the country, where a camp has been set up, along with a second near Marmatiei. Romanians have also taken to social media to organize donations of food and clothing for the refugees.
- Hungary -
Nearly 85,000 people have so far crossed from Ukraine into Hungary, UNHCR said.
Several border towns such as Zahony have set up public buildings as reception centres, with ordinary people donating food and clothes, the interior ministry said
- Moldova -
At least 70,000 Ukrainians have also crossed into Moldova, the country's deputy prime minister said Sunday.
The UN refugee agency said Monday that more than 36,000 Ukrainians had crossed into the country, adding that others had moved on to other European countries.
The UNHRC's central Europe chief Roland Schilling hailed the small nation for its response to a "heartbreaking situation".
He said local people as well as the Moldovan government "have been really impressive" in the way they are dealing with the flow.
Prime Minister Natalia Gavrilița visited the border crossing of Palanca Saturday where a tent village and medical facilities have been set up.
"In these dark days for Ukraine, we stand by its citizens," she tweeted. "Moldova will assist those in need of safe transit or shelter. We are with you Ukraine!"
- Slovakia -
The UNHCR said some 30,000 people had fled Ukraine into Slovakia since Thursday. The Slovak ministry of interior told AFP that 6,514 crossed on Sunday between midnight and 6 am alone.
- Belarus -
More than 300 people had crossed from Ukraine into Belarus, the UNHCR said.
- Onward movement -
The UN refugee agency said Monday that around 34,600 of those who had fled Ukraine into neighboring countries had already moved onwards towards other European countries.
- Internally displaced -
Some 160,000 people are thought to be internally displaced within Ukraine.
"Displacement in Ukraine is growing but the military situation makes it difficult to estimate numbers and provide aid," Grandi tweeted Saturday.
But the EU crisis commissioner Janez Lenarcic said Sunday that "we are witnessing what could become the largest humanitarian crisis on our European continent in many, many years," with up to seven million displaced and 18 (million) "affected in humanitarian terms".
© Agence France-Presse