The number of refugees fleeing the conflict in Ukraine has surged to nearly 875,000, UN figures showed on Wednesday, as fighting intensified on day seven of Russia's invasion.

In all, 874,026 people have fled across the country's borders, according to the website of UNHCR, the UN refugee agency.

That marks a huge jump of around 200,000 from the 677,000 announced almost 24 hours earlier by UNHCR chief Filippo Grandi.

Poland has welcomed around half of all those who have fled, according to combined tallies up to Tuesday.

UNHCR figures show that 454,000 had fled to Poland; 116,000 to Hungary; 79,000 to Moldova; 67,000 to Slovakia; 45,000 to Romania, 43,000 to Russia, and 350 to Belarus.

Meanwhile 70,000 have gone to other European countries.

Czech Prime Minister Petr Fiala said Wednesday that his country had welcomed around 20,000 Ukrainian refugees since the conflict started.

"The military offensive in Ukraine has caused destruction of civilian infrastructure and civilian casualties and has driven many thousands of people from their homes," UNHCR said.

875,000 refugees on the move from Ukraine

Nearly 200,000 people have fled Ukraine in just 24 hours, bringing to 875,000 the number of refugees seeking shelter in neighbouring countries since the full-scale Russian military invasion began on February 24.

The UN Refugee Agency (UNHCR) has projected that more than four million Ukrainian refugees may eventually need protection and assistance, while the European Union's crisis management commissioner has said the figure could reach seven million.

More than 37 million people lived under the Kyiv government's control before last week's invasion.

Here is a breakdown of where the 874,026 refugees have headed to:

- Poland -

Just over half of those who have fled Ukraine have crossed west into Poland.

The UNHCR said Wednesday that 453,982 people had done so. Most arrivals are women and children from all parts of Ukraine.

Polish officials have said that anyone fleeing Ukraine will be welcomed, whatever their nationality.

Polish border guards said 98,000 people entered from Ukraine on Tuesday.

- Hungary -

Some 116,348 people have so far crossed from Ukraine into Hungary, the agency said.

Thousands of refugees have arrived in Budapest. An AFP photographer saw dozens of refugees disembarking from trains arriving every 30 minutes in the Hungarian capital from the Ukrainian border on Tuesday.

Several border towns such as Zahony have turned public buildings into reception centres, with ordinary people donating food and clothes, the interior ministry said.

- Moldova -

UNHCR said 79,315 people who fled Ukraine were now in Moldova.

An airlift from Dubai was due to arrive on Wednesday bringing more emergency supplies for refugees.

- Slovakia -

The UNHCR said 67,000 had fled across Ukraine's shortest border to Slovakia.

"The government is maintaining an open and welcoming policy towards refugees, and has rapidly changed asylum laws to help fast-track asylum procedures," the agency said Tuesday.

- Romania -

The UN Refugee Agency said 44,540 people who fled were now in Romania.

Some refugees reported they had headed to Romania to avoid  massive jams at the Polish border.

Most are passing through Siret in the north of the country, where a camp has been set up, along with a second near Sighetu Marmatiei, where volunteers were handing out hot tea, coffee and pizza, as well as flowers and little charms to mark the beginning of spring,  celebrated on Tuesday across the country.

Officials said tens of thousands of refugees who entered Romania have now moved on elsewhere.

- Russia -

The UNHCR said 42,900 people had fled across Ukraine's longest border since the invasion began -- around five percent of the total number.

- Belarus -

Some 341 people had crossed north from Ukraine into Belarus, the UNHCR said.

- Onward movement -

The refugee agency said 69,600 of those who had fled Ukraine into neighbouring countries had already moved onwards towards other European states.

Czech Prime Minister Petr Fiala said Wednesday his country had welcomed around 20,000 Ukrainian refugees since the conflict started.

- Internally displaced -

Karolina Lindholm Billing, the UNHCR representative to Ukraine, estimated Tuesday that a million people had been internally displaced by the invasion.

She cautioned that the agency still did not have reliable figures.