TEHERAN (BLOOMBERG, REUTERS, AFP) - An Iranian navy vessel sank in the Gulf of Oman due to a fire that broke out during a training mission, the Islamic Republic of Iran Army said on Wednesday (June 2).

Crew of the "Khark" vessel were safely transferred to the coast but the ship sank off the Iranian port of Jask after 20 hours of operations to put out the blaze, according to an army statement on its website.

The vessel - the navy's largest - was used as a support and training vessel by Iran's navy for over four decades, it said.

The incident took place during training in the Gulf of Oman, a sensitive waterway that connects to the Strait of Hormuz through which about a fifth of the world's oil passes. Iran regularly conducts exercises in the area.

The statement did not give the cause of the fire.

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 pipeline from Bushehr province on the Gulf to Jask was put into service just days ago, the government said.

It will provide a new bypass route for oil exports avoiding the Strait of Hormuz.

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.

It was the latest in a reported series of attacks on Israeli- and Iranian-owned cargo ships since late February in which the two arch-enemies accused each other of responsibility.

Last year, an Iranian warship accidentally struck another with a missile during an exercise, killing 19 sailors and wounding 15 others.