KYIV (Reuters) - Russian forces have resumed air strikes on and are trying to storm the Azovstal steel works where Ukraine's remaining forces in Mariupol are holding out, Ukrainian presidential adviser Oleksiy Arestovych said on Saturday.

       "The enemy is trying to strangle the final resistance of the defenders of Mariupol in the Azovstal area," Arestovych said on national television.

       (Reporting by Pavel Polityuk; Writing by Alessandra Prentice; Editing by Mark Heinrich)