The Marine Department determined that they were not authorised to fish in the area, but the sole suspect in custody had already been released on bail.

“Last week, we received reports from divers that there was a yacht anchored at Koh Ha and that the people on board were suspected of shooting fish,” park chief Kankasem Meesook said. “At Koh Ha, we found a yacht named ‘Is A Kind Of Magic’ at anchor there. Nearby, we found two men diving, shooting fish with spears and taking photographs. We also found two other men and a child on the boat,” he said.

Officers seized equipment, including spears, a GoPro camera, diving equipment and accessories, two buoyancy control devices, a radio communication device and about 10 kilograms of fish. “We charged them and ordered them to move the boat ashore … We took one of the men with us on our boat and asked the rest to follow us,” said Kankasem.

“Initially, the others followed us on their yacht, but then they suddenly manoeuvred away and escaped. We chased them, but they were able to get away,” he said.

Nakhon Pathom native Waritnan Pronanon, 45, the only suspect in police custody, refused to provide any further information. He was nevertheless granted release on bail at the request of the governor of an unspecified eastern province. No reasons for the request were stated.

“We already know the names of the others and that they have escaped to Phuket, so we have asked the Phuket Marine Office to help us find them,” Kankasem said, adding that the yacht – which was not registered – normally docked at a Phuket pier but had not yet returned to the pier as of press time.

Police initially refused to give the nationalities of the other suspects.

The story went viral on social media, drawing criticism that officers had let the suspects escape custody.