A search is continuing for 31 missing sailors from HTMS Sukhothai, which sank on Sunday evening about 20 nautical miles (around 37 kilometres) off the coast of Prachuap Khiri Khan with 106 crew onboard.
As of Monday evening, 75 crew members had been rescued by search and rescue teams, aided by two helicopters and the crew of HTMS Angthong, HTMS Bhumibol Adulyadej and HTMS Kraburi.
According to navy spokesman Adm Pokkrong Monthatpalin, HTMS Sukhothai was on patrol off the coast of Prachuap Khiri Khan's Bang Saphan district when it was battered by high waves and strong winds.
The ship listed sharply and took on water, which damaged its electrical systems and caused the engines to fail. Without power, the corvette listed even further and eventually capsized, he said.
At 8.40pm on Sunday, HTMS Kraburi arrived with water pumps to help Sukhothai's crew try to salvage the sinking corvette, but they were unable to do so due to the rough conditions.
The Sukhothai sank at 12.12am, just as two private tugboats and an oil tanker arrived to help the stricken ship.
Two Seahawk helicopters were able to drop eight rafts near the ship, allowing some survivors to pull themselves from the water.
As of press time on Monday, 31 crewmen remained missing.
Adm Pokkrong denied reports which claimed that ten more people had been rescued, one of whom had died, saying those details were referring to the Anuphum, a cargo vessel which also capsized on Sunday.
He also said the search and rescue operation had been expanded to cover an area of about 16 square kilometres. On Monday, the navy asked all vessels to stay clear of the search area.
Responding to claims that HTMS Sukhothai sank because it was carrying 106 people when it was only designed to carry 87, Adm Pokkrong said the 87-man limit only applied when the ship was fully loaded with its full complement of weapons.
He said a fact-finding inquiry would be launched to look into the sinking, along with a salvage operation to raise the ship from the sea bed.
Separately, Prime Minister and Defence Minister Prayut Chan-o-cha has instructed the navy to mobilise their resources for the search and rescue mission, according to defence spokesman Gen Kongcheep Tantravanich.
Meanwhile, the Thai Maritime Enforcement Command Centre (Thai-MECC) on Monday called on local residents in nine provinces along the Gulf of Thailand and the Andaman Sea to closely monitor weather forecasts on an hourly basis after several vessels, including HTMS Sukhothai capsized on Sunday.
According to Thai-MECC Region 1, the Anuphum encountered heavy seas about 5.7 nautical miles from Chumphon, which caused the ship to list.
The cargo ship's ten crew were rescued by another vessel, the Pataravarin 88, it said.
Thai-MECC Region 2 also reported that the trawler Sor Nopparat 4 capsized about 30 nautical miles southwest of Koh Samae Sarn, although fortunately, all of its crew were rescued safely.
The merchant ship Santhat Samut 2, which was carrying nine crew members and a cargo of timber, sent a distress signal before the ship sank about 35 nautical miles from Samui.
All of the ship's nine crew members were safely rescued, and some 30 containers were spotted near the shore in Surat Thani's Chaiya district, the office said.
Meanwhile, the oil tanker Pattarapun, was swept towards the shore by strong winds, causing it to run aground in the mouth of Songkhla Lake.
The company which operates the ship will tow the tanker back out to sea when the conditions permit, an official said.