Russian forces captured the southeastern Ukrainian city of Melitopol on Saturday, Russia's Interfax news agency reported, as Moscow launched coordinated cruise missile and artillery strikes on several cities, including the capital Kyiv.

Ukrainian officials were not immediately available for comment on the fate of Melitopol, a city of about 150,000 people. If confirmed, it would be the first significant population centre the Russians have seized since their invasion began on Thursday.

Earlier, Ukrainian officials said Russian forces fired cruise missiles from the Black Sea at Mariupol, as well as Sumy in the northeast and Poltava in the east.

Kyiv authorities said a missile hit a residential building and a Reuters witness said another hit an area near the airport. There was no immediate word on casualties.