Iran's largest naval ship, the Kharg, sank on Wednesday morning after fire swept through the vessel from bow to stern.
State-affiliated media, including the Tasnim news agency, published video footage from the rescue effort.
All crew members were rescued from the 207-metre long vessel, according to reports.
Fire reportedly broke out at about 2.25am and quickly grew out of control. The ship was abandoned in the Gulf of Oman, near the Strait of Hormuz and the Iranian port of Jask.
The loss of the Kharg leaves Iran without a second support ship, after damage to the MV Saviz, which was attacked in the Red Sea in March with limpet mines.
The Saviz did not sink, but was put out of action for an extended period after explosions caused its engine room to flood.
Video reportedly of #Iran|ian Navy IRIS Kharg this morning burning and sunken approx. 6 miles off of Jask Port. FIRMS data has a hotspot around 25.652726,57.640181. pic.twitter.com/X4IlKPXH0w
— Aurora Intel (@AuroraIntel) June 2, 2021
The Kharg has been described as a logistical support ship, carrying fuel and supplies for other vessels, as well as being able to carry helicopters.
Like many of Iran's large surface vessels, it was ageing and may have suffered maintenance problems.
The Kharg was bought from Britain in 1977 as a civilian vessel, before being adapted for the Iranian Navy in 1984.
Iran is forced to reverse-engineer spare parts for ships purchased from abroad because of international sanctions preventing the import of new components.
Iran's navy is also prone to training accidents.
In May last year, 19 Iranian sailors were killed when the Konarak was struck by an Iranian missile. The vessel had been towing a target ship for a missile test.
While the loss of the Konarak was accidental, the fate of the Kharg could prompt speculation that a foreign state had conducted a sabotage operation, following the attack on the Saviz.
The Saviz, which Iran claimed was a civilian vessel, was long thought to have had a military role.
"Saviz is, foremost, a floating armoury ship," Farzin Nadimi, an analyst at the Washington Institute for Near East Policy think tank, told The National at the time.
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