Russia on Thursday said the flagship of its Black Sea fleet was seriously damaged and its crew evacuated following a fire that caused an explosion, as a Ukrainian official said the vessel had been hit by missiles.

The incident on the Moskva missile cruiser occurred after ammunition on board blew up, the Interfax news agency quoted the Russian Defense Ministry as saying.

"As the result of a fire on the Moskva missile cruiser, ammunition detonated," it said in a statement.