Victoria's anti-corruption watchdog says police could still be conducting false breath tests.

The reputation of the state’s police force was rocked last year by the revelation that officers had falsified 258,000 breath tests to return negative readings.

Officers were either placing a finger over the straw of the entry hole of the breath testing equipment or blowing into the straws themselves in order to obtain false readings.

Investigations revealed that even new recruits were being taught how to fake breath tests so that officers could meet a target for 99.5 per cent of roadside breath tests to come back negative.

In its annual report, the Independent Broad-based Anti-Corruption Commission (IBAC) said more breath tests may be falsified, as police are still held to the targets previously found to be “meaningless and unachievable”.

Responding to the IBAC report, Victoria Police said tests are no longer being falsified because it management made it “absolutely clear” that the practice was not acceptable.

“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.”

Significantly more people died on Victorian roads last year 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 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.”