(Reuters) -The missile cruiser Moskva, the flagship of Russia's Black Sea fleet, has sunk in stormy seas following a major fire onboard, Russian news agencies cited the defence ministry as saying on Thursday.

       The defence ministry had said earlier that the Soviet-era warship had been badly damaged by the fire. Ukraine, however, said the shipboard blaze resulted from its missile strike. Reuters was unable to verify either account.

       "During the towing of the cruiser 'Moskva' to the port of destination the ship lost stability due to the damage to the hull received during the fire from the detonation of ammunition," the agencies cited the ministry as saying.

       "In the stormy sea conditions, the ship has sunk."

       The ministry reiterated that the crew had been evacuated.

       (Reporting by Reuters; writing by Lidia Kelly; editing by Jonathan Oatis)