Police say they have cancelled almost 600 speeding and red light camera fines issued by virus-infected road safety cameras so Victorians do not lose confidence in the traffic camera system.

The fines had been issued by 55 affected cameras in Melbourne and country Victoria between June 6 and June 22.

Victoria's Department of Justice and Regulation said a software virus was mistakenly introduced by a contractor.

Acting Deputy Police Commissioner Ross Guenther said he believed the cameras were operating correctly despite the virus.

"However, given the independent nature of the [Road Safety] Camera Commissioner, I think it'd be wrong for me to assume that that's the case until he's had the opportunity to look at all the circumstances resulting in their issuing the fines," he said.

Police, the sheriff and the commissioner, John Voyage, will hold an inquiry next week.

Acting Deputy Commissioner Guenther said his key message was that traffic cameras saved lives.

"I cancelled the fines because I think it's important the public has confidence in the system — 100 per cent confidence," he said.

"So, until I'm satisfied from the meetings next week that that's actually the case, I think the public would expect that those fines are withdrawn."

A total of 590 fines had been issued by the virus-affected cameras. Only three of the fines were serious so-called "loss of licence" infringements.

Mr Voyage also stressed the importance of maintaining Victorians' confidence in the system.

"I think people have no reason to lose confidence in the road camera safety system," he said.

"There is nothing to compromise the accuracy of the cameras; there's no reason why anyone would think that inappropriate infringement notices were delivered."