Instead, he ordered troops to seal off the area so tightly that even “a fly cannot not pass through”.

In a phone call, Maksym Zhorin, a senior official of the Azov battalion based in Kyiv, said the Russian leader’s comments proved his troops were struggling to make progress against the much smaller force defending the industrial plant.

“The Russians have just admitted their possible defeat,” he said. President Putin changed tack, he added, because “they're not able to occupy the Azovstal”.

Though the invading forces control nearly all of the southern port city, they have not been able to dislodge the Ukrainians from the steelworks. The fighters there are made up of Azov troops – a controversial group with links to the far right – and marines.

Zhorin alleged the Russians had bombed civilian air shelters in the city, and that they had used cluster bombs and white phosphorus munitions in a bid to clear the Ukrainians.

The BBC has not independently verified these claims but has found cluster munitions being used elsewhere in the conflict.

And Zhorin declared the battle for Mariupol to be like "a test for the world".

"Whether humanity can react, can unite, in order to save innocent civilians," he said.

You can read more about President Putin’s order and the defenders of Azovstal here.