First soldiers leave Mariupol steelworks

"Fifty-three seriously injured were evacuated from Azovstal on 16th May for medical assistance," Malyar said. 

"A further 211 persons were taken through a humanitarian corridor to Olenivka. An exchange procedure will take place for their return home."

The General Staff of Ukraine's Armed Forces said early on Tuesday that the servicemen defending the Azovstal steel plant against Russian forces had fulfilled their combat mission.

"The supreme military command ordered the commanders of the units stationed at Azovstal to save the lives of the personnel," the General Staff said in a statement on its Facebook account. 

"Efforts to rescue defenders who remain on the territory of Azovstal continue."