Manas Dasgupta
NEW DELHI, Mar 4: An Iranian naval vessel “IRIS Dena,” a Moudge-class frigate, which was returning to Iran after participating in the MILAN 2026 multinational naval exercises in Visakhapatnam, has sunk off the coast of Sri Lanka, after what officials say may have been a submarine attack, leaving at least 140 Iranian sailors still “missing.”
The Sri Lankan forces. Sri Lankan authorities said, launched a massive rescue operation after receiving a distress message and so far 32 people who were on board the ship have been rescued, while over 140 are still missing, according to Sri Lankan foreign minister Vijitha Herath, who informed parliament about the incident.
Officials said the navy received a distress call from the Iranian ship and launched a search and rescue operation with the support of the Sri Lankan air force in the Indian Ocean off the island’s coast. The cause of the sinking remains unclear. While some defence sources suggested the vessel may have been attacked by a submarine, Sri Lanka’s navy said it had not observed any other ship or aircraft in the area.
According to officials, the frigate was about 40 nautical miles off the coast of Galle when it reported an explosion and began sinking. The vessel was believed to be carrying around 180 crew members at the time of the incident. Sri Lankan officials said hopes were fading for many of the sailors believed to have been aboard the Iranian warship.
The vessel belonging to the Iranian Navy’s Southern Fleet, issued a distress call around 5.30 am local time while operating roughly 40 nautical miles off the coastal city of Galle, Sri Lankan defence officials said. The sinking occurred amid a rapidly escalating conflict involving the United States, Israel and Iran. Military strikes launched by the United States and Israel on February 28 targeted Iranian military infrastructure and killed Iran’s Supreme Leader, Ayatollah Ali Khamenei, along with several senior officials, according to US and Israeli statements.
“We estimate that the frigate had approximately 180 sailors aboard at the time of the incident. We suspect that between 100 and 150 crew members were still unaccounted for as of Wednesday afternoon,” said a top government official in Colombo. Mr Herath confirmed in parliament that Sri Lanka had launched a rescue mission after receiving the distress call from the Iranian vessel. He said the ship was sinking just outside Sri Lanka’s territorial waters but within the country’s designated search-and-rescue zone. “We responded to the distress call under our international obligations,” Navy spokesman Buddhika Sampath told the media. Two naval ships and a surveillance aircraft were dispatched to assist with the rescue.
Officials did not publicly confirm the cause of the incident. But two senior Sri Lankan government officials said early information gathered from the scene suggested the warship may have been struck by a submarine-launched weapon.
“It appears consistent with a submarine strike,” one senior official said. “However, the specific submarine responsible has not been identified, and the investigation is ongoing.”
Another official said the government could neither confirm nor rule out the involvement of a United States submarine operating in the region. “The US Navy Ohio-class submarines routinely patrol the Indian Ocean from the American military base on Diego Garcia (a strategic island facility used for operations across the Middle East and Asia). We are examining sightings and maritime tracking data,” he said.
Iranian naval deployments in the region have been relatively rare. The IRIS Dena had been participating in diplomatic naval activities in the weeks before the incident. In February, the frigate attended the International Fleet Review in the Indian port city of Visakhapatnam, where it docked alongside ships from multiple countries. The Indian Navy had extended a warm welcome to the frigate as it arrived in Visakhapatnam in the third week of February.
The Moudge-class frigate, named after Mount Dena in south-western Iran, is a domestically built warship designed for patrol and combat missions in regional waters. It displaces roughly 1,300 to 1,500 tons and carries a range of anti-ship missiles, naval guns and torpedo launchers. The ship also includes a helicopter landing pad and radar systems capable of tracking multiple targets.
A military analyst said the vessel would have been heavily armed, carrying Qader anti-ship missiles, a 76-millimetre naval gun and torpedo systems, among other weapons. Sri Lankan authorities said they were withholding video footage of the rescue operation because it involved the military assets of another country.
Sri Lanka has maintained a policy of neutrality in international conflicts but occupies a strategically significant location along major shipping routes in the Indian Ocean. The waters south of Sri Lanka lie near some of the world’s busiest maritime corridors linking Asia, the Middle East and Europe. Naval vessels from multiple countries, including the United States, China and India, regularly transit or patrol the region.