Over 80,000 people have used humanitarian corridors to flee areas surrounding Ukraine’s capital, Kyiv, and the northeastern city of Sumy in the past two days, Ukraine’s deputy prime minister, Iryna Vereshchuk, said during a news conference on Thursday.

In a video posted to her Telegram profile, Ms Vereshchuk detailed the evacuations, saying that 60,000 civilians had evacuated in the Sumy region and roughly 20,000 others were evacuated from areas northwest of Kyiv, including Irpin, Bucha and Hostomel. An additional 3,000 people fled “with difficulty” from Izyum, a city in eastern Ukraine, she said.

Russian forces have surrounded or nearly surrounded a number of Ukrainian cities and are destroying much of their critical infrastructure, making evacuations increasingly difficult, if not impossible.

Conditions are particularly dire in the port city of Mariupol, a city of roughly half a million people that has been under siege for more than a week, with its water, electricity and food supplies cut off.

“A humanitarian disaster is ongoing in Mariupol,” Ms Vereshchuk said.

More than 2.3 million people have fled Ukraine since Russia’s invasion began on Feb 24, and an additional 1.9 million are displaced within the country, according to UN officials.

On Thursday, the UN spokesman Stéphane Dujarric said that as refugees are moving west, away from the front lines, the humanitarian situation “continues to deteriorate at an alarming pace.”