A Russian warship in the Black Sea was “seriously damaged” on Wednesday, according to a Ukrainian military official and Russian state news agencies, though each claimed a different cause for the destruction.

The head of Odesa’s military forces, Maxim Marchenko, said on Telegram that Ukrainian forces had struck the ship with anti-ship Neptune missiles. He claimed it was the same vessel that was famously and obscenely told off by Ukrainian troops in February, saying it went “exactly where it was sent by our border guards on Snake Island!”

Hours later, Russia’s Ministry of Defense said that ammunition had exploded on the ship, a missile cruiser called the Moskva, as a result of “a fire,” according to the state news agency Tass. The agency reported that the crew had evacuated from the ship and that the cause of the fire was under investigation.

Neither account could be independently confirmed. If Mr. Marchenko’s claims are correct, the damage to the warship would mark a notable military triumph for Ukraine — the formidable Moskva is the flagship vessel of Russia’s Black Sea Fleet.

The ship, which is more than 600 feet long, first entered service in the early 1980s with the Soviet Navy and carries 16 Vulkan missile launchers with a strike range of more than 400 miles, Russian news agencies have reported. It was deployed off the coast of Syria in 2015 to provide air defenses and patrolled the coast of Georgia during a conflict with Russia in 2008.

Ukraine has repeatedly claimed to have destroyed Russian warships since the start of the war, but its reports have not always been independently verified.

In March, Ukraine’s military said it had destroyed a Russian ship at the port of Berdiansk, under Russian occupation in southern Ukraine, and videos and photos reviewed by The New York Times confirmed that a Russian ship was on fire at the port.