At least 34 people have been killed, as the US envoy to Ukraine says the strikes cross "any lines of decency".

Over 20 people were killed by a Russian missile strike on the northern Ukrainian city of Sumy on Sunday, its acting mayor Artem Kobzar said. "The Russians hit the city of Sumy with missiles, killing civilians,

More than 30 civilians were killed after Russian missiles hit the city of Sumy in north-eastern Ukraine, according acting mayor Artem Kobzar, while dozens more were injured.