"Despite all the statements by Russian officials that Mariupol is under their full control, this is not true. Azovstal, the stronghold – the last stronghold of Ukrainian resistance in Mariupol — still holds," Kuleba said in a Twitter livestream Wednesday.

Read here Ukrainian forces in Azovstal plant: contact has been lost

In an interview with Radio Svoboda, Ukrainian parliament member David Arakhamia confirmed that Russian troops have already reached the premises of the Azovstal steel plant. Arakhamia, who has led Ukrainian delegation in talks with Russia, also confirmed that Ukrainian authorities had managed to regain communications with Ukrainian fighters at Azovstal after losing touch with them earlier on Wednesday.

The soldiers and civilians still in Azovstal continue to suffer "endless attacks" from Russian forces, Kuleba said, stressing that the sustained artillery fire and aerial bombardment are putting their lives at risk.