At a meeting of the committee chaired by Sen Veerapun Suvannamai on Thursday, the focus was on reviewing the proposed legislation and scrutinising the essential details of the draft law.

Prime Minister Paetongtarn Shinawatra was invited by the committee to explain the government's stance. However, she was away on an official visit to Vietnam and instead delegated the task to Deputy Finance Minister Julapun Amornvivat.

Mr Julapun was also unable to attend as he was accompanying the premier on the Vietnam visit. Ms Paetongtarn's appointment was then postponed to June 5, according to Sen Veerapun.

The committee proceeded with discussions of the academic aspect of the bill instead.

Committee adviser Sen Chirmsak Pinthong raised concerns about the government's draft bill, suggesting it was a disguised attempt to legalise large-scale casinos.

He criticised it for granting excessive powers to a policy board chaired by the prime minister. He describes the board as the "casino cabinet".

The draft law vaguely limits state revenue generated from casino concessions to no more than 5 billion baht rather than setting a clear minimum, raising transparency concerns.

He also questioned why concessions would be granted without a bidding process, with no public hearing or environmental impact assessment on the project.

Mr Chirmsak pointed to rumours about potential casino sites, including a 3,800-rai plot of land at Klong Toey Port in Bangkok. Acquiring the site would necessitate revising the Port Act, with a land value estimated to be around 1.2 million baht per square wah.

If they use just 10% of that land for a casino, the investors will have the right to access land worth 100 billion baht. But investors would, in return, pay the state just 1.1 billion baht in concessions annually.

Other proposed sites include Chiang Mai's San Kamphaeng district and Chon Buri's U-Tapao area.

Mr Chirmsak warned that the 30-year casino concession would create a burden for future generations if things did not go according to plan.

Kaewsan Atibhoti, a committee member, said the project may be designed to benefit foreign investors.