The flagship of Russia’s Black Sea fleet has sunk after what Kyiv said was a Ukrainian missile strike, dealing one of the heaviest blows yet to Moscow’s war effort and providing a stunning symbol of Kyiv’s resistance against a better-armed foe.

Kyiv says it hit the cruiser Moskva with missiles fired from the coast. Russia did not confirm the attack but said the ship sank while being towed in stormy seas after a fire caused by an explosion of ammunition. Moscow said more than 500 sailors had been evacuated. There was no independent confirmation of the fate of the crew.

Although Russia did not acknowledge that Ukrainian missiles had hit the ship, early on Friday it struck what it described as a factory in Kyiv that made and repaired anti-ship missiles, in apparent retaliation.

The Moskva was by far Russia’s largest vessel in the Black Sea fleet, equipped with guided missiles to attack the shore and shoot down planes, and radar to provide air defence cover for the fleet.