Kharg, the largest vessel in Iran's navy, sank early Wednesday in the Gulf of Oman near the port of Jask, Hormozgan province, after being ablaze for nearly 24 hours, Iranian news agencies have reported. 

Tasnim News Agency reported that a fire broke out around 11am local time Tuesday and the ship sank 8.30am Wednesday, after efforts to extinguish the fire failed.

Tasnim, which described Kharg as a logistics-training vessel, said all 400 crew and trainees aboard had been evacuated with 20 people hospitalized with minor burns.

Kharg had been on a "training, intelligence and combat mission" in international waters along with Alborz, an Alvand-class frigate, according to a statement from the naval force of the regular Iranian army May 9.

Behzad Jahanian, an army press spokesman, said Wednesday the cause of the fire had not been identified. He described the ship as one of Iran’s most advanced and the second largest in the Middle East after Makran, also an Iranian vessel. Many on social media have mentioned an initial explosion as the cause of the fire.

Hossein Aryan, a former Iranian naval officer who is familiar with Kharg told Radio Farda in an interview that the quick sinking of the vessel makes it more likely that there was an explosion in the engine room or below the water line.

Suspicion of sabotage, evident in social-media speculation, is inevitable with continuing Israeli threats against Iran following a series of spectacular attacks against high-value targets widely believed to have been the work of Israeli agents.

Yossi Cohen, the outgoing chief of Mossad, Israel’s external intelligence agency, said on Tuesday that “We penetrated into the heart of hearts of the enemy Iran.”

Cohen was referring to operations that gathering pace since 2018. In early July 2020, an explosion hit a sensitive section of Natanz uranium enrichment facility, destroying the assembly hall for new machines. This was followed by the killing of nuclear scientist Mohsen Fakhrizadeh in November and the April 11 attack on Natanz.

Saviz, a ship operated by Iran’s Revolutionary Guards, was attacked, possibly by a limpet mine, in the Red Sea on April 6 off the coast of Eritrea. An American official said Israel had called the attack retaliation for earlier alleged Iranian strikes on Israeli vessels.

Kharg − an auxiliary ship with fuel tanks and dry cargo that can supply both fuel and dry stores at sea − was ordered by Iran from the United Kingdom in 1974 and launched in 1977. The vessel was delivered to Iran in 1980, a year after the 1979 Revolution, and became operational in 1984 when Britain issued an export license for the ship after lengthy negotiations. 

The over-200-meters long Kharg could displace over 11,000 tons of standard load and up to 33,000 tons at full load and had a gross tons of 18,500 tons. It could also launch helicopters.