Western countries attending a UN Security Council meeting have condemned Russia for destroying a theater in the eastern Ukrainian city of Mariupol, where civilians were taking shelter.

The Security Council met on Thursday to discuss the humanitarian situation in Ukraine. The United States, Britain and other countries requested the emergency meeting.

UN Under-Secretary-General Rosemary DiCarlo told the delegates that the use of powerful weapons in populated areas has caused many casualties.

She said the "magnitude of civilian casualties" cannot be denied. DiCarlo also said, "This demands a thorough investigation and accountability."

US Ambassador to the UN Linda Thomas-Greenfield said, "The Russian word for 'children' was written outside the theater, both front and back, in large white letters that could have been seen from the sky. Yet Russian forces bombed it anyway." She added, "Russia will be held accountable for its atrocities."

Ukraine's UN ambassador Sergiy Kyslytsya said Russian pilots dropped a bomb and fully damaged the theater, even though the word "children" was written on the ground. He said children are being deliberately targeted.

Russia's UN ambassador Vassily Nebenzia repeated Moscow's claim that its forces have not targeted civilians and civilian facilities, including the Mariupol theater.