Victoria's deputy police commissioner has shunned calls for a royal commission, insisting police will hunt down the rat in their ranks who leaked secret files to criminals.
Deputy Commissioner Simon Overland said police were "furious" that confidential files had been leaked to a suspected drug trafficker and a suspected murderer.
But the police union has claimed there is a political motive behind the report of the leaks, saying it was handed to the media to help push a "draconian" bill through state parliament.
Police Association secretary Greg Davies had demanded that Mr Overland substantiate what he called damaging "rumours" contained in the story, published in The Age on Tuesday.
He said it had been handed to the media to drum up support for a bill that would expand the powers of commanders to immediately sack corrupt officers.
"There is no doubt whatsoever that this story was timed to occur today," Mr Davies told reporters.
"We haven't said it was released by police command, we don't know by who it was released. But it is unbelievable that this story was embargoed until today and today was the very day that these amendments were due to be debated in the upper house."
Earlier, Mr Overland told reporters that at least one officer was involved in leaking two "target profiles" from the state surveillance squad, a covert unit monitoring suspects' movements in terrorism, organised crime and serious offence cases.
"What we have here is certainly a corrupt officer, we believe," Mr Overland said.
He said police wanted to "get rid of" corrupt officers and pointed to the bill.
"It's one of the reasons why we've gone back to government and asked them to change the discipline system ... to give us the capacity to actually remove these sorts of people from the organisation," he said.
He rejected calls for a royal commission or a new body to oversee police operations, saying the Office of Police Integrity (OPI) had the same powers as a royal commission.
Having known about the leaks since the middle of the year, Mr Overland said "going public" would assist police and OPI investigations.
"Obviously, there's been a limit to what we can do overtly within the state surveillance unit because that may well have alerted the person or persons responsible to our interest," he said.
"An added reason for going public today is that it now allows us to make those sorts of inquiries internal to the unit."
But Mr Davies said Mr Overland should use the information to charge someone.
"Until there is a thorough investigation completed, we won't know who has been involved, the public won't know who has been involved and the public deserves to know.
"Now, if Mr Overland has that information then perhaps that should be brought forward so people can be charged and have their day in court and be convicted or acquitted and then everybody will know."
Mr Davies said "continuing rumour-mongering" hurt police morale as well as community confidence.
He called for the OPI to investigate the leaking of the story to the media on behalf of "the overwhelming majority of innocent members of ours who work at the surveillance unit".
Victorian Police Minister Bob Cameron said Chief Commissioner Christine Nixon informed him of the allegations on Monday and he spoke to Mr Overland about it that night.
"This is a very, very serious matter and one that is being taken very seriously," Mr Cameron told parliament's lower house.