The Iranian Navy's support vessel IRIS Kharg has sunk off the southern port city of Jask, following a blaze on board that could not be extinguished after an hours-long battle.
The ship sank on Wednesday in the Gulf of Oman near the strategic Strait of Hormuz leading to the Persian Gulf.
The incident had no fatalities and all 400 crew members and trainees on board safely disembarked before the vessel went down.
A 20-hour effort to extinguish the fire by the ship's damage control team, which were joined by firefighting crews as well as military and civilian forces from other nearby vessels, failed to save Kharg, according to a spokesperson for the Navy.
However, the spokesperson noted that all crew members and trainees aboard the ship were evacuated and transferred to safety.
Only 20 out of the 400 people on board received minor injuries.
Reports suggested the blaze had begun at around 11 a.m. local time on Tuesday with thick black smoke rising from the ship.
The fire, which according to the navy official started at the vessel's engine room, gradually spread out of control and engulfed the ship, eventually causing it to sink.
Kharg, the official said, was the second largest logistics vessel in the region after Makran. It was named after the Kharg Island in the Persian Gulf.
The vessel, which had been in service for forty years, was used for both logistical and training purposes.
The navy spokesman said the cause of the fire was still under investigation, and a statement will soon be made in this regard.