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Russia's defence ministry on Friday confirmed for the first time that the crew of the missile cruiser Moskva suffered casualties when it blew up and sank last week, a report from RIA news agency indicated.
Russia initially said all the ship's crew had been evacuated after an ammunition blast triggered by a fire ripped through the Moskva, the flagship of its Black Sea fleet.
"Attempts by the crew to extinguish the fire were not successful," RIA quoted the defence ministry as saying.
"During the struggle to stabilise the ship, one serviceman died and another 27 crew members went missing. The remaining 396 members of the crew were evacuated."
Ukraine says it hit Moskva with an anti-ship missile but western security officials were unable to confirm that Ukraine-designed prototype Neptune missiles, which have a range of 315 kilometres, were responsible.
The Moskva is the second major ship known to have sustained serious damage since the start of the war. Last month, Ukraine said it had destroyed a landing support ship, the Orsk, on the Sea of Azov.
Russia's navy has launched cruise missiles into Ukraine and its activities in the Black Sea are crucial to supporting land operations in the south of the country, where on Friday it said it had "liberated" the port of Mariupol.
Last Saturday, the defence ministry released footage of what it said was the head of the navy meeting with about 100 Moskva crew members.
What is the Russian warship 'Moskva'?
Defence experts have told The National that, despite being the flagship of the Black Sea Fleet, the Moskva was old, having been commissioned in 1983, and had several maintenance upgrades cancelled.
Built in the Soviet era in Ukraine's Mykolaiv, the Moskva entered service in the early 1980s, Russian media report.
With a crew of 510, it was used in the Syria conflict, where it served as naval protection for the Russian forces' Hmeimim airbase.
The missile cruiser carries 16 P-1000 Vulkan anti-ship missiles and an array of anti-submarine and mine-torpedo weapons, the reports said.
The Moskva gained notoriety early in the war when its captain called on Ukrainian border troops defending the strategic Snake Island to surrender, which they refused to do.
The troops were initially believed to have been killed but were taken captive.
They were released as part of a prisoner exchange with Russia in late March, the Ukrainian Parliament said.