The most important ship in Russia's Black Sea fleet, the Moskva missile cruiser, was badly damaged after ammunition on board blew up, Interfax news agency quoted the Russian defence ministry as saying on Thursday.
Interfax said the crew had all been evacuated and the cause of the fire was being investigated. A Ukrainian official earlier said the ship had been hit by two missiles but did not give any evidence for the claim.
(Reporting by David Ljunggren; Editing by Muralikumar Anantharaman)