If punters cannot select the numbers they want to buy, the new lottery with designated numbers needs to have a large jackpot to attract attention, in order to reduce the chance of punters "wasting their money" with operators of the underground lottery, the panel said.

Finance Minister Chalongphob Sussangkarn, who chaired the meeting, said equipment might have to be introduced to keep sales of the free-selection option below 60 per cent of overall ticket sales, as required by the law.

"Special equipment might be needed to measure whether [free selection] sales exceed 60 per cent, otherwise it's against the Government Lottery Office law," he said.

Chalongphob dismissed widespread press reports that he had set June 2 as the date for the new system to begin operating.

He said a legal interpretation of his panel's conclusion might be needed to prevent the lottery bill from being shot down during scrutiny by the National Legislative Assembly (NLA).

Ammar Siamwalla, a noted academic and an NLA member, said the government always needed to keep in mind that the new two- and three-digit lottery system was aimed at making people addicted to gambling, gamble less.

"If everything is done in the same way the previous system was operated, it means that gambling will increase," he said.

He added that a thoroughly planned state-run lottery could never be operated at a loss, because punters were guaranteed payments of prize money and the underground lottery operators could never offer a jackpot prize.