The Federation of Thai Spa Associations (FTSPA) has urged authorities to clamp down on sexual services being offered at some massage parlours.
Apichai Jearadisak, an adviser to the FTSPA, revealed that some government officials and influential people have used growing spa services and legal loopholes to open "pretty spas" or massage parlours where tourists can buy sexual services.
"This has damaged the image of Thai spas. The government should do something to crack down on this problem," he said.
Spas have become a key tourism product in the medical and wellness sector in recent years but only 500 of the 2,000 spas nationwide are legally registered.
The FTSPA expects the number of registered spas will increase significantly but the business is related to many government agencies.
The Public Health Ministry directly supervises the spa business but has no knowledge of massage and spa services. The Commerce and Tourism and Sports ministries have set a revenue target at least 20 billion baht per year from the spa business but they never focus on quality control, Mr Apichai said.
There are also seven associations and two clubs related to the spa business.
The low-end spa segment is highly competitive. Clients can pay only 150 baht per hour for general massage, while Thai spas overseas in countries such as Japan often charge 1,600 baht per hour.
The big price gap has caused many overseas Thai spas to train alien workers as masseuses, according to the FTSPA.
Mr Apichai said employing migrant workers as masseuses has ruined the nature of Thai spas, which should feature internationally recognised Thai traditional massage techniques and Thainess.
Rangsiman Kingkaew, president of the Phuket Spa Association, said the government should seriously supervise the Thai spa business by setting standards and growth directions.
About 57% of foreign visitors to Phuket use spas, according to the association.
Mr Rangsiman said the government should speed up setting standards to prevent misunderstanding between real Thai traditional massage and poor massage services on beaches and roadsides.
Preeda Tangtrongchitr, director of Wat Po Thai Traditional Medical School, said many foreign citizens registered for massage training at the school. Its students have worked in 135 countries to introduce traditional Thai massage.