The Narcotics Suppression Bureau (NSB), US Drug Enforcement Administration (DEA) and law enforcement officers from other countries are working together to clamp down on the problem.
The markets are in Asia, the US, Europe, South America and Australia, said Sangsuraya Karnasut, commander of NSB Division 1.
A coordinator for Siwapong Pattanapongpanich, a NSB superintendent involved in campaigns to clamp down on illegal steroids, said Thailand had become a major production base for steroids.
The substance is popular among professional athletes who want to quickly build muscles and strength. It is considered a controlled substance in many countries. In the US, possessing it is subject to punishment by narcotics law putting it in the same category as marijuana possession.
But Thai law treats illegal steroids differently. Its production comes under food and drug laws which allow for more lenient punishments than the Narcotics Act which can be used to impose the maximum penalty of a death sentence. The maximum penalty for violating food and drug laws is a jail sentence.
This leniency in Thailand’s steroid prohibition laws, and the drug’s popularity with athletes, lures both foreigners and locals to use the kingdom as a base to produce and sell them, said Pol Maj Gen Sangsuraya. He said chemicals used to make steroids were not hard to find.
The coordinator for Pol Col Siwapong, who requested anonymity, said steroids were also not difficult to produce. Making steroids requires some expertise but producers do not have to be specially trained chemists.
A recent crackdown by authorities underlined concerns about the problem.
On July 30, the NSB, the Office of the Narcotics Control Board (ONCB) and the Food and Drug Administration (FDA) raided a house on Soi Charoen Krung 79 and four other places in the capital.
They found illegal steroids in tubes and bottles altogether worth about 100 million baht. Working on the information provided by the DEA, the NSB spent about two years trying to track this network.
An American based in Hong Kong was believed to have financed the operation by hiring Thais, including Rung Sunthornkanit, 41, to produce and deliver it after orders were sent to a website and money had been transferred.
Ms Rung confessed to police after the arrest, Pol Maj Gen Sangsuraya said. She faces five charges under food and drug laws. Orders from foreign clients were worth from 4 million to 7 million baht a month, the office said. One small bottle of a steroid made for 100 baht in Thailand can be sold for US$100 (3,200 baht) in the US.