Bryan Kidman, who has worked on the casino's gaming floor for more than 16 years, said employees were in the dark about staffing levels, wages and conditions ahead of a looming shift in the ownership structure of the city casino.

Blue Whale Entertainment is awaiting ACT government approval on a complex deal which will see it become the majority shareholder in the companies which own and operate the casino, Aquis Entertainment Limited and Casino Canberra Limited.

The government is completing a probity review of the deal, which marks the final step in the approval process. The company's board and shareholders have already green-lighted the proposal, which was announced in December.

A government spokesman could not put a time frame on the completion of the review.

Mr Kidman, who is a delegate for the hospitality workers' union, United Voice, said neither Aquis or Blue Whale had provided workers with written assurances about their employment conditions once the deal was complete.

Mr Kidman said the union approached Aquis earlier this year seeking to negotiate a new pay deal, as the existing agreement was due to expire on June 30.

The union was told that talks would not start until the sale was complete, prompting it to ask for a "letter of intent" stating that existing working conditions would be retained under the new owners.

It also sought guarantees that, following the sale, there would be no forced redundancies, changes to hours or rosters or any outsourcing of work.

The old agreement has since expired, although the conditions will remain in force until a new deal is struck.

"If they won't give us an undertaking about the conditions, then there must be a reason for that," Mr Kidman said.

"There is just the uncertainty of not knowing what our conditions are going to be. People are a bit worried in the hospitality industry because of what has happened in the past.

"We are not being told anything, we've had no information."

The acting chief executive of Casino Canberra and Aquis, Allison Gallaugher, said it was premature to start negotiations with the union before the government's probity review was finalised, and the sale approved.

However, Ms Gallaugher said Blue Whale had intentions to grow the business, which she said could "only be a good thing for all our employees".

She rejected Mr Kidman's claims that employees had been left in the dark.

"Our employees are regularly updated in staff meetings on the status of the transaction and have also been reassured directly regarding their job security and the potential opportunities which will exist for all of them and the business, on completion of probity," she said.

A government spokesman said while it could not force Blue Whale to retain staffing levels or conditions, it hoped it would "consider the wellbeing of their existing employees during the transition".

The Canberra Times reported in March that Blue Whale would consider outsourcing the management of the venue if the deal was approved.

The company has also forecast updates at the casino, including new restaurants and upgrades to gaming facilities.

Casino management also recently re-started talks with the ACT government about its $330 million expansion proposal, after the bid was knocked backed last year.