This week authorities in Phang Nga, the province north of Phuket, were told that the Ani-Corruption Commission would join the probe to weed out salaried government workers who are thought to be behind the scam.
The corruption is fairly widespread and simple to execute, officials told the meeting. Police from Region 8 headquarters were also in attendance, along with natural resources and anti-corruption officials.
Admission tickets to the seven national parks - including two islands spots, the Similans and Surin, popular with divers - are 200 baht for non-Thais and 40 baht for Thais.*
It's believed that tickets are copied and sold to overcome restrictions on numbers at some of the parks that are designed to maintain sustainability.
Checks on tourists' tickets within the parks uncovered the scam. Officials believe the 16 million baht income from the parks last year will increase substantially once the corruption is suppressed.
Authorities agreed on a two-part solution - the pursuit of those who are already employing the scam, followed by the introduction of better technology to make sure it cannot be repeated.
As well as on the Similans and Surin islands, investigations are to take place at Khao Lak-Lamroo, Khao Jampee-Taimuang, Moo Khan Rah-Khah Pratong, Sri Phang Nga and Ao Phang Nga national parks.
Vice Governor Supachai Luengsangtong is heading the investigation.
*We've since been informed tickets for the Surin and Similan parks are 400 baht for Thai adults/non-divers and 600 baht for non-Thai adults/divers.