Russian forces fired missiles at the centre of the eastern Ukrainian city of Kramatorsk in an air strike on Thursday, and there were casualties, the city's mayor said.

"Air strike with missiles on central parts of Kramatorsk, there are casualties," Mayor Oleksandr Goncharenko wrote on Facebook, without providing details of the casualties. He urged residents to remain in shelters. (Reporting by Aleksandar Vasovic; Editing by Timothy Heritage)