Victoria's anti-corruption watchdog has warned of a repeat of the police force's fake breath test scandal, which could undermine "public confidence" in the entire road safety program.

Key points: Victoria Police has a target of 3 million breath tests during 2019-2020

Victoria Police has a target of 3 million breath tests during 2019-2020 IBAC said the risk of falsifying tests remained because of the "unachievable" targets imposed on police

IBAC said the risk of falsifying tests remained because of the "unachievable" targets imposed on police Police said they were confident the practice had stopped

An internal police investigation revealed in May last year that more than 258,000 breath tests were estimated to have been falsified by Victoria Police officers to return negative readings.

In its annual report, the Independent Broad-based Anti-Corruption Commission (IBAC) said it was concerned more breath tests could be falsified, because police still needed to meet targets previously found to be "meaningless and unachievable".

Officers had been found to either place a finger over the straw of the entry hole of the breath testing equipment or blowing into the straws themselves.

The investigation found new recruits were taught how to fake breath tests and officers were told to meet a target where 99.5 per cent of roadside breath tests would come back negative.

Responding to the IBAC report, Victoria Police said it was confident tests were no longer being falsified because it had been made "absolutely clear" that the practice was not acceptable.

IBAC oversaw Victoria Police's investigation which said the "meaningless" targets led to police faking breath tests to meet quotas.

"IBAC is concerned that the quantitative measure has been retained with one minor amendment," the report said.

"The number of alcohol screening tests during 2019-2020 is to be 3 million rather than 3.5 million.

"This risk of falsification remains … and in turn affects public confidence in Victoria Police's road safety program."

Questions over effectiveness of targets

The report questioned whether the targets were necessary, given last year significantly more people died on Victorian roads than the previous year.

"It is timely to closely examine the alcohol and drug targets, to ensure these targets support, rather than hinder, road safety," the report said.

"Victoria Police has advised that although the 99.5 per cent target for 2019-20 remains … it is no longer applied.

"Victoria Police will need to work internally and with external stakeholders to ensure that retention of the 99.5 per cent target does not create perverse consequences."

Victoria Police Assistant Commissioner Stephen Leane said he was confident the practice is no longer taking place.

"We have made it absolutely clear to our police that the practice is not acceptable and we continue to implement the recommendations identified in the initial report," he said.

"Victoria Police has committed to delivering three million preliminary breath tests in the 2019-20 financial year, as articulated in this year's state budget.

"This measure has been adjusted to reflect what is achievable by Victoria Police."

Assistant Commissioner Leane said it was important that police got the balance of road policing priorities right, while remaining focused on getting drink drivers and those who were affected by alcohol off the roads.