Ukrainians are facing long waits at border crossings into neighbouring European countries as more people continue to flee escalated attacks from Russian forces on some of Ukraine's most populous cities.

CTV National News' Daniele Hamamdjian is at the Medyka crossing in Poland where she says lines on the Ukraine side stretch back dozens of kilometers. It is the busiest border crossing between Poland and Ukraine.

If crossing the border by car, Ukrainians are being told they could be waiting anywhere between three and 35 hours. Those crossing by foot may be waiting up to 60 hours to cross.

"We understand that Polish officials are letting everybody in, but for those who don't have official documentation, didn't have time to grab their passports and their IDs, they will be able to come through, but they will be housed in a separate accommodation and they will be monitored," Hamamdjian said.

According to the UN refugee agency UNHCR, more than 800,000 people have fled Ukraine as of Wednesday morning to neighbouring countries since the start of Russia's invasion last week.

Watch the full video with CTV National News' Daniele Hamamdjian at the top of the article

Â鶹´«Ã½ map graphic by Jasna Baric

Ukraine map