An Iranian naval vessel sank in the Gulf of Oman Wednesday after efforts to put out a fire failed, but the crew safely disembarked, the navy said.
The fleet replenishment tanker Kharg had caught fire on Tuesday near the port of Jask on the Gulf of Oman.
Kharg catches fire
The fire broke out in "one of the systems" of the vessel, a navy statement said without elaborating.
Firefighting efforts continued "for 20 hours" before the ship went down, it said.
"Considering the spread of the fire, the mission to save the Kharg failed and it sank in waters off Jask."
Strait of Hormuz
It added that the vessel had left for a "training mission" in international waters days ago.
Last year, an Iranian warship was hit by friendly fire during a naval exercise off Jask, killing the 19 sailors onboard.
The port lies close to the Strait of Hormuz, the strategic chokepoint at the head of the Gulf through which a fifth of world oil output passes.
Jask is also important to Iran's economy as the site where the government plans to build the country's second-largest oil export terminal.
A 1,000-kilometre (620-mile) pipeline from Bushehr province on the Gulf to Jask was put into service just days ago, the government said.
The pipeline will provide a new bypass route for oil exports avoiding the Strait of Hormuz.
In recent months, there have also been reported attacks on Iranian shipping linked to its arch foe Israel.
In April, Iran said its freighter Saviz was hit by an "explosion" in the Red Sea, after media reports said Israel had struck the ship.
Saviz targeted in Red Sea
In April, Iran said one of its vessels, the Saviz, had been targeted in the Red Sea, after media reports the ship had been attacked with limpet mines.
That came after Israel and Iran had blamed each other for a series of reported attacks on cargo ships since late February.
Iran has refused to recognise Israel since its Islamic Revolution in 1979 that toppled the US-backed Shah. Israel sees Iran's nuclear programme as a threat to its existence.
The shipping incidents have occurred since US President Joe Biden took office in January, pledging to rejoin Iran's 2015 nuclear containment deal with six world powers - abandoned by his predecessor Donald Trump in a move welcomed by Israel - if Tehran returns to full compliance with the accord.
No further explanation was given for the latest incident in a region of sensitive waterways, where there have been accusations of attacks on ships owned by arch-enemies Iran and Israel.