ZAPORIZHZHIA, Ukraine (Reuters) - A convoy of buses carrying evacuees from southeastern Ukraine, including some 40 civilians who had been holed up in the Azovstal steel plant in besieged Mariupol, arrived on Sunday in the Ukrainian-controlled city of Zaporizhzhia, a U.N. official said.

       Osnat Lubrani, the U.N. humanitarian coordinator for Ukraine, said eight buses had arrived in the city. About 40 of the 174 evacuees on board had been rescued from the steel plant.

       Lubrani said in a statement that the evacuations brought to more than 600 the number of people evacuated from the area in the past 10 days.

       "Our work, however, is not yet done," she said in the statement. "The UN is aware that scores of people who wanted to join the evacuation convoys over the last days were unable to do so.

       "We will continue our engagement with both parties to the conflict to make sure that those who want to leave have the guarantees to do so safely and in the direction of their choice."

       (Reporting by Alessandra Prentice; Editing by Ron Popeski, Andrea Ricci and Leslie Adler)