KYIV (Reuters) - A senior Ukrainian official said on Friday a new attempt was under way "at the moment" to evacuate civilians trapped with Ukrainian fighters in the Azovstal steel works in the southern city of Mariupol.

       Andriy Yermak, the head of the presidential staff, gave no details and it was not immediately clear what stage the new rescue effort was at.

       U.N. Secretary-General Antonio Guterres told the SecurityCouncil on Thursday that a third operation was under way to evacuate civilians from Mariupol and Azovstal.

       "The next stage of rescuing our people from Azovstal is under way at the moment. Information about the results will be provided later," Yermak said.

       (Reporting by Pavel Polityuk, Editing by Timothy Heritage)