Many male tourists who visited Phuket for sex found themselves losing consciousness after kissing the breasts of sex workers.
According to Hong Kong's Apple Daily, the men found their money and valuables missing after they regained consciousness.
One of the girls from the syndicate, Joob, 24, said more than 10 women were involved, and that men from Hong Kong, China, Taiwan and Singapore were their targets.
"They are more timid and usually won't lodge a police report afterwards," Star Online quoted her as saying.
"Normally, we can find a few thousand Thai bahts on them," she said.
Joob also said that 1,500 baht (RM150) was given to the mastermind each time they pulled off the stunt.