More than 500,000 people have fled Ukraine since Russia invaded the country last week, according to the UN refugee agency.

UN High Commissioner for Refugees Filippo Grandi gave the estimate in a tweet.

The latest and still growing count had 281,000 people entering Poland, more than 84,500 in Hungary, about 36,400 in Moldova, over 32,500 in Romania and about 30,000 in Slovakia, UNHCR spokeswoman Shabia Mantoo said.

The rest were scattered in unidentified other countries, she said.

Another train carrying hundreds of refugees from Ukraine arrived early on Monday in the town of Przemysl in southeastern Poland.

In winter coats to protect them against near-freezing temperatures, with small suitcases, they lined up at the platform to the exit.

Some waved at the cameras to show they felt relief to be out of the war zone.

Many were making phone calls.