Smoke rises above a plant of Azovstal Iron and Steel Works company and buildings damaged in the course of Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 18, 2022.
Smoke rises above a plant of Azovstal Iron and Steel Works company and buildings damaged in the course of Ukraine-Russia conflict in the southern port city of Mariupol, Ukraine April 18, 2022. Reuters / ALEXANDER ERMOCHENKO

Russia is preventing wounded Ukrainian fighters from being evacuated from a vast steel works in the southern city of Mariupol because it wants to capture them, the local governor said on Thursday.

Pavlo Kyrylenko, governor of the eastern region of Donetsk, said Russia was also blocking efforts to arrange humanitarian corridors elsewhere in Donetsk but that Russian forces were being held back across his region.

Hundreds of fighters and some civilians are holed up in the Azovstal steel works, their last redoubt in Mariupol. Russian forces have been pummelling the factory after laying siege to Mariupol for weeks, but President Vladimir Putin has said the plant need not be stormed.

"They (want to) use the opportunity to capture the defenders of Mariupol, one of the main (elements) of whom are the... Azov regiment," Kyrylenko told a briefing, referring to a group of fighters that Moscow has vilified.

"Therefore the Russian side is not agreeing to any evacuation measures regarding wounded (Ukrainian) troops."

Kremlin spokesman Dmitry Peskov said Putin had been quite clear that while civilians could leave the plant, the defenders had to lay down their arms, Tass news agency said.

"What could be the topic of negotiations in this case?" the agency quoted him as saying.

Moscow denies targeting civilians in what it says is a special military operation to disarm Ukraine and defeat nationalists there. The West calls that a bogus pretext for a war of aggression.

Mariupol city council said about 100,000 city residents were "in mortal danger" because of Russian shelling and unsanitary conditions. It said the shortage of drinking water and food was "catastrophic".

Russia has mounted a push to seize Donetsk and another eastern province in the second stage of its invasion.

"The (new offensive) is ongoing now for a second week, and the enemy has not met its tactical or strategic aims," Kyrylenko said.

He said Russia had "not once" observed agreements reached on establishing humanitarian corridors. Russia has said Ukraine is to blame for the failure of talks on safe corridors.

Kyrylenko said that despite the lack of agreements on humanitarian corridors, only 370,000 residents remained in Ukrainian-controlled parts of the Donetsk region compared to 1.67 million before Russia's invasion.

Over 270,000 have fled the Donetsk region on trains and nearly 80,000 have gone by road, he said.