Four full-time employees will be made redundant and casual shifts cut as the opening time is moved back 3½ hours to 4.30pm. Closing time will remain at 4am.

Efforts to make the casino viable appear to be faltering, with the latest job losses and changes to hours following similar steps in January last year. .

In its 1990s heyday, the venue operated around the clock with more than 600 staff.

Marketing director Peter Cursley said the decision to cut the jobs came during difficult economic conditions and pressures on the gaming industry.

''Normally, 60 per cent of a casino's revenue comes from gaming machines and we're probably the only casino in the world that doesn't have them,'' he said.

''We've asked staff to put their hands up for voluntary redundancies. We obviously want the impact to be as minimal as it possible.''

He said the cuts were an effort to protect the remaining 250 staff.

''What [the job cuts] will allow us to do is basically have a very good chance of breaking even,'' he said.

''The problem is that to open a table game, there are mandatory staffing levels we have to abide by … whereas two people could probably run 100 gaming machines.''

Mr Cursley said the ACT government's block on a long-standing proposal for 200 gaming machines was likely to continue, but direct flights to Canberra from Asian capitals could provide a boost to revenues.

Staff were first informed of the cuts to jobs and opening hours in a meeting last week, with the union United Voice saying the cuts would have devastating impacts on employees.

ACT branch secretary Lyndal Ryan the decision was a ''backwards step''. ''Frontline staff hear the comments made by customers and players … saying that if the casino is not going to be open they will just go up the road.

''From our members' point of view, the reduced number of table games being played at any one time is concerning, and they think if people arrive at the casino outside of the opening hours then their business will be lost.''

Ms Ryan said the introduction of gaming machines could also have adverse impacts on staffing levels.

''It is a double-edged sword … our members are keen that the casino be viable and that they have jobs, but electronic gaming machines need less people to operate them.''

In March, the casino offered to give the ACT government land in Civic for expansion of the National Convention Centre, in exchange for the poker machines licences.

Management offered to pay generous up-front licence fees, contributing to $4 million a year in territory revenue through gaming taxes.

Gaming Minister Joy Burch indicated the policy against poker machines at the casino would remain in place.