Mr Ferrar's comments put a question mark over a project that has already made only slow progress since the casino announced plans in 2015 for a major expansion with swank hotels and brand shopping, dependent on being given the right to operate poker machines. Clubs are fighting hard to maintain their monopoly and the Greens say they will only support the move if the casino's have a spin limit of less than $5, compared with the $10 spins in clubs, and the first mandatory precommitment scheme in the country, with gamblers forced to nominate upfront how much they are prepared to lose on the pokies over 24 hours.

The government introduced a bill in August, but it leaves the difficult questions unresolved, such as the spin limits, tax rates and how much of the redevelopment will go ahead. The bill includes $5 spins by the government and the Greens are still negotiating.

The Gaming Technologies Association, which represents the big poker machine manufacturers including Aristocrat, has rejected the regime.

"The bill would result in the equivalent of a miniature, separate casino jurisdiction with unique requirements. The process of developing a unique portfolio of games for such a jurisdiction is not financially feasible," Mr Ferrar has told the ACT government's justice directorate in answers last week to a series of questions.

Mr Ferrar told The Canberra Times that some jurisdictions had $5 spins, but the games had to be separately developed and tested, then externally retested for each jurisdiction based on the rules of each, adding layers of complexity and expense. If the ACT mandated $5 spins, games would need to be developed and rested all over again - which would not be feasible for a single venue with just 200 machines.