Vic cops 'tarnished' by fake breath tests

A former police chief will head an investigation into faked breath tests by Victoria Police

A former Victorian police chief will lead an investigation into why officers faked more than a quarter of a million breath tests over five years.

An audit by the force's Professional Standards Command has revealed the falsification of 258,463 out of 17.7 million breathalyser tests since 2012, and former police chief Neil Comrie is tasked with finding out why.

Officers faked the tests by either placing a finger over the straw entry hole or by blowing into the straw themselves. A leading theory is they wanted to appear more productive.

"Victoria Police is incredibly disappointed. It is incredibly poor behaviour by our members," Professional Standards Command Assistant Commissioner Russell Barrett told reporters on Thursday.

The main culprits were general duties and highway patrol officers, with some rural areas over-represented, but Mr Barrett said it was too early to say how many police were involved.

Mr Comrie, a former Victorian police chief commissioner, will lead an investigation into why officers faked the tests.

Police oversight body, the Independent Broad-based Anti-corruption Commission, is in ongoing discussions with Victoria Police about the scope of their investigation.

"Police have significant powers and the community rightly expects them to use these powers honestly, responsibly and to perform their duties fairly, impartially and always in accordance with the law," IBAC commissioner Robert Redlich QC said.

"The evidence that Victoria Police officers have falsified tests is deeply concerning, as is the evidence of a culture that has enabled this to occur and not be detected or immediately dealt with."

The scandal has led Victoria's Transport Accident Commission to suspend funding to the police force.

About $12 million over three years is made available but police need to apply to use funds for specific purposes, and recent applications have been suspended until the issue is resolved.