The Kharg, Iran’s biggest ship, burns and sinks.

TEL AVIV: Iran’s largest warship, the Kharg, caught fire on Wednesday in the Gulf of Oman and sank. The fire, sources here say, was very strange and the smoke generated by the fire demonstrates “something big went wrong.”

The Kharg caught fire while sailing in international waters. She was engaged in a training exercise, Iranian media said.

According to the Tasnim news agency, the fire started in the engine room, causing parts of the ship to melt and fall into the sea.

Rescue workers tried for 20 hours to extinguish the fire but couldn’t stop it, Tasnim said. Iran’s navy has said the nearly 400 crew were evacuated safely from the ship.

No one has claimed responsibility for the fire but Middle Eastern sources say that for some time it was closely “observed” since it is the biggest ship in the Iranian navy.

The Strait of Hormuz and nearby areas have been the scene of several confrontations recently between Iran, the US and other countries. Last month, for example, the US warned Iran after more than a dozen Iranian fast attack boats buzzed close to a US Navy submarine and escort ships in the Strait of Hormuz. The US fired warning shots when the boats approached too closely at speed. The Iranians claimed the US the engaged in “aimless, unnecessary and provocative shooting.”

Middle Eastern sources say that if the fire on the Kharg was caused by an “outside” force this may raise questions about whether the ship was not just a supply vessel, but performed other missions.