Nineteen sailors have died and 15 others wounded after one Iranian warship accidentally struck another with a missile during an exercise.
According to state television, who were quoting the navy, the incident took place during training in the Gulf of Oman on Sunday (May 10).
It's a sensitive waterway that connects to the Strait of Hormuz, through which about a fifth of the world's oil passes.
State broadcaster IRIB said the frigate Jamaran fired at a training target released by a support ship, the Konarak.
However, the support ship stayed too close to the target and was hit.
Some sections of the Iranian media are reporting that the Konarak had sunk.
But the Fars news agency quoted an unidentified military official who denied this.
It is unclear which is true.
The state broadcaster said the Dutch-made Konarak vessel was purchased before Iran's Islamic revolution in 1979 but was overhauled two years ago and is now equipped with four cruise missiles.