The warship, identified as the Iranian Navy frigate IRIS Dena, was reportedly attacked by a foreign submarine while operating outside Sri Lankan waters, defence sources told the Daily Mirror.

According to Sri Lanka’s Defence Ministry, 101 sailors remain unaccounted for, while 78 others sustained injuries in the incident. The vessel was carrying approximately 180 crew members at the time, the newspaper reported. The frigate had issued a distress call earlier in the day before sinking off Sri Lanka’s southern coast.

Foreign Minister Vajitha Herath told Parliament that injured sailors rescued from the vessel had been taken to a hospital in southern Sri Lanka for treatment.

Sri Lanka Navy spokesman Buddhika Sampath said that two naval vessels and an aircraft had been deployed to assist with search and rescue operations, in line with the country’s international maritime obligations. “We are continuing the search, but we do not yet know what happened to the rest of the crew,” an official told the newspaper, raising concerns about the chances of finding additional survivors.

The incident comes amid heightened tensions in the Middle East following an Israel-US attack on Iran that resulted in the death of Supreme Leader Ayatollah Ali Khamenei. In retaliation, Iran launched missiles and armed drones targeting US military bases and critical energy infrastructure, sparking fears of a broader regional escalation.