Reports says, as many as 19 Iranian sailors are dead and at least 15 injured after a rocket fired during a training exercise in the Gulf of Oman hit a ship near the port of Jask, around 1,270 kilometres south-east of Tehran.
According to reports, the rocket had hit the Konarak, which was tasked with putting targets in the water for other ships to fire upon. At least 12 sailors were admitted to hospital, with a further three treated for minor injuries.
Iran initially said one sailor had been killed on Monday but then hours later updated the death toll to 19.
A Dutch manufactured vessel that was given the capability to fire sea and anti-ship missiles in 2018, the Konarak had been in service for more than 30 years and usually carries a crew of 20 sailors.
It is unusual for Iran to publicly-admit accidents that take place on training exercises.
Iran often carries our exercising in the Gulf of Oman, which is close to the Strait of Hormuz, through which some 20% of global oil supplies pass.
The Strait is the entrance to the Persian Gulf, the strip of water that separates Iran from its geo-political rivals the United Arab Emirates and Saudi Arabia.
In May 2019, U.S. aircraft carrier Abraham Lincoln was sent to the Middle East in May over tensions with Iran. The ship previously had been in the Arabian Sea outside of the Persian Gulf.