The five foreigners were checking in with seven suitcases for a flight from the resort island to Singapore at 6pm on Wednesday when police pulled them aside to have the bags searched, said Pol Col Denduang Thongsrisook, chief of the Bo Phut police station, reports the Bangkok Post.
UK citizens Mark Siemaszkiewicz and Richard McMahon, both 46, had four suitcases containing 85.3kg of cannabis buds. Their British compatriots Peace Adefila, 27, and Esther Fakuade, 26, had two suitcases with 35.8kg of cannabis.
The four were planning to take another flight from Singapore to Britain. They said Thai men had asked them to bring the bags to the UK in exchange for either debt repayment or £2,000 (about B87,000), according to Pol Col Denduang.
The street value of the cannabis haul in the UK is estimated at a minimum of B15 million.
The Malaysian, Tan Chin Tick, 47, was carrying a bag containing 22.8kg of cannabis buds. He had been hired for 6,000 ringgit (about B45,000) to smuggle the bag to Singapore, his final destination.
Pol Col Denduang said police were expanding their investigation to find the mastermind of the smuggling ring.