While the main goal of the parole system is to maintain the safety of the community, acting Auditor-General Peter Frost said there was always the risk some people on parole would re-offend.

"The alternative to parole is prisoners being released from prison with no support or supervision," he said.

In his audit report tabled to the Victorian parliament on Wednesday, Dr Frost said there was evidence people on parole committed fewer crimes than those released straight from jail into the community.

While no Victorian data is available, Dr Frost pointed to 2014 NSW research that showed parolees were less likely to commit new offences than prisoners who were released straight from prison into the community.

"It also found that those who did reoffend took longer to do so and committed fewer new offences."

Victoria's parole system has been the subject of fierce scrutiny over the past five years, after a spate of serious crimes, including murder, committed by former prisoners on parole hit the headlines.

In 2013 and 2014, the former state government introduced a suite of reforms to the parole system, including new rules that the Parole Board must take into account when it decides whether prisoners are allowed parole.

Dr Frost said since those reforms, bolstered by $84.1 million in funding, the administration of parole had improved. He said the parole board was now better informed and resourced, and parole officers better trained and supported.

Prisoners now have to apply for parole rather than being automatically considered by the parole board, and parole conditions have been tightened, particularly for serious offences.

All serious violent or sexual offenders are now required to complete programs while in prison, but the department does not monitor how many of these offenders have completed the required offending behaviour program by their earliest eligibility date for parole.

But Dr Frost found there were also problems that could have long-term effects on community safety.

"Fewer prisoners are being released on parole," he said. "Those who are not released on parole are not subject to parole officer supervision upon release and cannot be ordered to undertake the community-based programs offered by DJR [the Department of Justice and Regulation] and service providers."

Men and women released from prison, including those on parole, are at sharply higher risk of dying than others in the community. The Coroners Court identified at least 233 ex-prisoner deaths between 2000 and 2013. Of those, the vast majority overdosed on drugs, with suicide by hanging being the second-most common cause of death.

Dr Frost said the department should monitor the deaths of parolees and investigate their causes, to better support people on parole.

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