Mr Farmer met with Mr Barr's chief of staff Jamie Driscoll on Friday and said he was "stunned" when Mr Driscoll raised the idea of increasing poker machine numbers so 500 could go to the casino.

But Mr Barr said on Sunday Mr Farmer was wrong.

"The government will not be increasing the number of poker machines in the ACT," he said. "Mr Farmer is a gun for sale and will push the agenda he is paid to on behalf of his clients. The Government will not be giving a running commentary on his paid advocacy."

Mr Farmer has been taken on by the Raiders clubs to campaign against the casino's bid for 500 poker machines as part of a $330 million redevelopment. His campaign is also funded by other big clubs, who say giving poker machines to the casino would devastate their businesses.

Canberra poker machine numbers are capped at 4994. The biggest four owners are the Vikings (715 machines), the Southern Cross Club (620), the Raiders (528), and the Labor Clubs (503).

In December, the Labor Club board passed a resolution saying it won't sell machines to the casino, potentially cutting off one source of machines. Mr Farmer said he had told Mr Driscoll the casino would struggle to find clubs willing to sell.

"I say, look that's a nonsense to say they'll get the 500. He said, 'We can of course just issue them with 500 new licences for machines'. At which point I spilt my coffee," Mr Farmer said. He stood by his claim, despite Mr Barr's denial.

Mr Farmer said the casino's poker machine bid made no sense, because not only would poker machines not bring international visitors, they would also not make sufficient money to justify a $330 million development. If each machine made $40,000 a year (the biggest clubs in Canberra make $30,000 to $55,000), the casino would make $20 million a year before tax.

Mr Farmer put an alternative to Mr Driscoll, suggesting the government could offer tax incentives to the casino to help it attract high rollers, allowing the casino to pay bigger payouts than rival casinos.

"At the moment the ACT government earns 100 per cent of nothing from high rollers. Wouldn't a suitable solution, instead of worrying about 500 poker machines that aren't going to be played by international visitors, be that they offer them a taxation rate that enabled them to compete – because 50 per cent of something is better than 100 per cent of nothing ...

"I thought the solution really was why don't you give the casino a put-up-or-shut-up option: If you mean what you say that you will attract all these international visits we'll give you a taxation rate to enable you to do it."

He had made the same suggestion to Greens Shane Rattenbury, who has asked his party to reconsider its opposition to poker machines in the casino.

Mr Farmer slammed the secrecy with which the bid was being considered, saying clubs were left fighting a proposal they knew little about.

"This chief minister is obsessed by, one, development deals and, two, doing them in secret," Mr Farmer said. "You just look at the community outrage at Manuka. This is not just a fight about poker machines, it's a fight about secret government backroom deals. There is absolutely no reason why you shouldn't make unsolicited development proposals fully open to the public."

Mr Farmer is upping pressure on the government in an election year, threatening to put together his own list of candidates to fight the casino move – a course of action he would have to begin within a few weeks.

"I've got about three weeks before we try to start taking steps that might well become irreversible," he said.