More than 260 Ukrainian soldiers were evacuated from the besieged Azovstal steel plant in the port city of Mariupol, Ukraine's Deputy Defence Minister Ganna Malyar said on Monday.

"53 heavily wounded (soldiers) were evacuated from Azovstal to the medical mortgage near Novoazovsk for medical aid," Malyar said in a statement.

Another 211 were taken out through the humanitarian corridor to Olenivka, she added.

Both Novoazovsk and Olenivka are now under the control of Russian troops and Russia-backed separatists.

"An exchange procedure will be carried out for their further return home," Malyar noted.

Ukrainian President Volodymyr Zelenskyy said "we hope to save the lives of our boys".

"I want to underline: Ukraine needs its Ukrainian heroes alive. This is our principle," he said in a video statement late on Monday.

Ukraine's general staff said the soldiers in Mariupol "performed their combat task" and now the main goal is to "save the lives of personnel".

By holding the Azovstal plant, Ukrainian troops did not allow Russians to rapidly capture the southern city of Zaporizhzhia, a statement on Facebook said.

"Defenders of Mariupol are the heroes of our time. They are forever in history," it added.

The Azovstal plant has become a symbol of resistance, with hundreds of troops continuing to fight on there even after the rest of the city had fallen to Russian forces. (AFP)