The action followed a trial run at the Melbourne casino during March and April, 2017, where certain buttons were hidden on 17 gaming machines over a three-and-a-half week period, so only minimum and maximum betting options were available.

In a statement on Friday, the Victorian Commission for Gambling and Liquor Regulation said the actions varied certain gaming machines and therefore the move had required its approval.

"Crown's failure to obtain approval means it has contravened the Gambling Regulation Act 2003," it said in a statement on Friday.

"This is the largest fine the commission has issued to Crown and reflects the seriousness with which it considers the matter."

The commission said the contravention was not deliberate and Crown fully co-operated with its probe.

Crown Resorts Limited said the contravention was not deliberate and that the gaming machine trial did not impact on the return-to-player ratio.

"While Crown Melbourne's position throughout this process was that the Gaming Machine Trial did not require the prior approval of the Commission, Crown Melbourne respects the Commission's decision, which brings this process to a close," it said in a statement.

The commission also asked Crown to provide an updated compliance framework within six months and explain how it will prevent a similar matter happening again.

Independent federal MP Andrew Wilkie, who took the former casino employee's concerns to parliament, welcomed the finding, but said the fine was not enough, given the severity of the misconduct.

"This is a very serious offence for which Crown should stand condemned," he said in a statement on Friday.

"However I do not accept Crown's explanation that this was only a trial, because there is an abundance of evidence that the practice has been more widespread."

Mr Wilkie said other allegations he raised remain unresolved and he hopes the commission can make findings on these as more evidence emerges.

Mr Wilkie said he continues to be approached by whistleblowers alleging serious misconduct at Crown, and will raise this with regulators and police when appropriate.

"I expect the Commission and the police to diligently probe these matters. It would be completely unacceptable to the community if they take the casino's explanations at face value or continue to hand out slap-on-the-wrist fines," he said.

Australian Associated Press