Mr Hargreaves, active in the Labor Party and patron of the Billiards and Snooker Association of the ACT, told the Legislative Assembly's inquiry into the clubs sector on Wednesday to raise the issue of a ban on notes bigger than $20 and declare current regulations ineffective in limiting problem gambling.

The association has called for "parity" between New South Wales and ACT poker machine regulations to stop punters going across the border, and for the community contribution paid by clubs in the territory to be increased from 8 per cent of net gaming revenue to 10 per cent.

ACT government figures from 2013-14 show clubs paid more than the minimum in community contributions, $12.7 million or 13.27 per cent.

Increasing the contribution would help support community organisations and sporting groups, Mr Hargreaves said.

He retired from the Assembly in 2012 but remains active in the party, including in Gaming Minister Joy Burch's southern Canberra electorate.

"As the gross gaming revenue reduces, so too does the amount of money which is available for community contributions so, by definition, if the revenue is down, there is less money to go to charitable organisations," he said.

Gamblers could easily get around the ban on $50 notes by changing them for smaller notes inside clubs, Mr Hargreaves told the committee.

"What happens though ... is the people who have an issue will go to the note breaker and do it anyway, but the casual person, who uses the poker machine as part of a night out, won't go and whack a $50 note in there.

"I am not going to be such a wet sop as to deny people the opportunity to have a bit of fun. If they have the ability, with their discretionary income, I am not going to say what they can do with it."

He also questioned findings presented to the committee by the Australian National University's Centre for Gambling Research, compiled from surveys of 7000 people in late 2014 and early 2015, including how problem gamblers playing online or at home could be considered in the study.

Greens Minister Shane Rattenbury told Mr Hargreaves the centre's prevalence study did consider other types of gambling and that note bans were found to be effective in helping problem gamblers limit their spending.

Mr Hargreaves disagreed.

"I've been around the club industry as a patron since the introduction of poker machines. I have seen more people sitting at the chairs in the Kippax and the Erindale TAB in absolute distress than I've ever seen in a club.

"You can have any academic do as much research as you like but I'm telling you from personal experience exactly how it works."

The centre's report showed problem gambling affected 0.4 per cent of ACT residents or about 1110 people, while 45 per cent of people have not gambled in the past 12 months, up from 30 per cent in 2009. There has been a 19 per cent fall in total expenditure since 2009.

Mr Hargreaves said because the government was "screwing clubs to the wall" on poker machine revenues, they should allow them to diversify their businesses through concessional lease arrangements.

A ban on $50 notes has been a vexed political issue for the Barr government amid its moves to overhaul gambling regulation and create a trading scheme to increase the number of poker machines.

In January, Mr Rattenbury forced Chief Minister Andrew Barr to reverse moves to allow $50 notes in clubs' machines, backing down on the change made by Ms Burch days immediately before Christmas last year.

Ms Burch made the move quietly, without a public announcement and without agreement of the cabinet.