The Royal Thai Navy has confirmed that the HTMS Sukhothai, a Ratanakosin-class missile corvette commissioned in 1987, had sunk in the Gulf of Thailand late on Sunday.
"The ship's operating systems stopped working, causing the ship to lose control," navy spokesperson Admiral Pogkrong Montradpalin told media, adding that the ship sank shortly after midnight.
The corvette, with 106 crew on board, had been on patrol about 20 nautical miles offshore from Bang Saphan district, Prachuap Khiri Khan province, when high waves forced it to list starboard at a 60-degree angle and take in water. This had disabled the ship's electrical power systems, with the Sukhothai losing propulsion. As water flooded the hull, the boat began to capsize.
The Royal Navy had immediately dispatched an amphibious ship - HTMS Angthong - along with frigates HTMS Bhumibol Adulyadej and HTMS Kraburi, as well as two seahawk helicopters to carry out a rescue operation.
According to an official statement, 78 of the crew had been rescued from the waters, with some 11 personnel being treated at Bang Saphan hospital. Three crew members were reportedly in serious condition. Another 40 rescued sailors were being housed at shelters, added reports, while the search-and-rescue operation was said to be ongoing.