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.

“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 onto other ships in the Black Sea.

It said it was still trying to establish the cause of the incident.

The defence ministry had said earlier on Thursday that the Soviet-era ship had been badly damaged by the fire, the latest setback for Russia which has suffered a series of blows since it sent troops into Ukraine on February 24 in what it called a “special military operation.”

Ukraine’s southern military command said on Thursday that it hit the Moskva with a Neptune anti-ship cruise missile. It said Russian rescue ships were then hampered by ammunition exploding on board as well as bad weather that had caused the Moskva to start sinking.

Russia’s navy has launched cruise missiles into Ukraine from the Black Sea to support its military activities in the south of the country, where it is battling to seize control of the port of Mariupol.