The head of Ukraine's Donetsk region, where Russian forces have made rapid but limited advances in recent days, has Wednesday ordered civilians with children to evacuate from towns and villages under threat.

"We are beginning the mandatory evacuation of families with children from the town of Bilozerske," governor Vadym Filashkin said, adding that around a dozen of other settlements fell under the orders well.

He said some 1,150 children remained in the area impacted by the order.