A third operation is underway to evacuate civilians from Mariupol and the besieged Azovstal steel plant in Ukraine, UN Secretary-General Antonio Guterres told the Security Council on Thursday.

The UN and the International Committee of the Red Cross (ICRC) helped nearly 500 civilians flee the area during two operations in the past week, Guterres said.

"In the first, concluded on May 3, 101 civilians were evacuated from the Azovstal plant, along with 59 more from a neighboring area," he said. "In the second operation, completed last night, more than 320 civilians were evacuated from the city of Mariupol and surrounding areas. 

"So far, in total, nearly 500 civilians found long-awaited relief, after living under relentless shelling and scarce availability of water, food, and sanitation." 

During his address, Guterres also called for an end to the "cycle of death and destruction" in Ukraine.