Military experts and journalists in Ukraine are warning that the sunken Russian warship Moskva could have carried nuclear weapons when it went down, the New York Post reported on Friday.

Ukraine claimed responsibility for sinking the ship with two Neptune anti-ship missiles about 60 miles off the coast of Odesa. A senior U.S. defense official also reiterated the claims, according to Wisconsin Public Radio.

However, Russia's Defense Ministry alleged that a fire broke out onboard, causing munitions to explode and prompting the evacuation of the ship's crew, believed to number around 500.

Regardless, some are sounding the alarm that the 12,500-ton ship could have been transporting weapons of mass destruction.

Mykhailo Samus, deputy director of the Center for Army Studies, Conversion and Disarmament, warned: "Onboard the Moskva could be nuclear warheads — two units," he posted on Facebook.

They would be in a "protected place," so "most likely they were not damaged by the explosion."

Meanwhile, on his Facebook account, Andrii Klymenko, editor in chief of Ukraine's BlackSeaNews portal, called for an international investigation into whether the Moskva was carrying nuclear weapons.

"Friends, experts say that there are two nuclear warheads ... on board ... Where are these fighting heads at? Where were they during the ammunition explosion? ... This is the competencies of the UN, IAEA [International Atomic Energy Agency]," Klymenko wrote.

"The countries of the Black Sea — Turkey, Romania, Bulgaria, Georgia should immediately join this" investigation, he added.

Ukraine's Defense Express online news outlet also cited the possibility that the warship may have sunk with dangerous nuclear warheads.

"The Moskva missile cruiser, which overturned and began to sink after being hit by R-360 Neptune missiles, is a carrier of nuclear weapons," it said in a report.

"In particular, these are anti-ship missiles P-1000 'Vulkan,' of which the ship has 16 units. Each of them can be equipped with a nuclear warhead with 350 (kiloton) capacity or a conventional 500-kg high-explosive cumulative," the report continued.

• US Official: Russian Ship Believed Hit by 2 Ukrainian Missiles
• The Russian Military Says the Damaged Moskva Missile Cruiser Sank While Being Towed to a Port