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, Interfax news agency quoted the Russian defence ministry as saying.
"As the result of a fire on the Moskva missile cruiser, ammunition detonated," it said in a statement.
Maksym Marchenko, governor of the region around the Black Sea port of Odesa, said in an online post that the 12,500 tonne ship was hit by two missiles, without providing evidence.
"Neptune missiles guarding the Black Sea caused very serious damage," he said in an online post.
Reuters was not able to independently verify either account.
Ukraine warned late on Wednesday that Russia was ramping up efforts in the South and East as it seeks full control of Mariupol, in what would be the first major city to fall.