Auditor-General John Doyle’s review of scrutiny of High Value High Risk projects found that the Treasury’s scrutiny of project benefits was insufficient and that there was inconsistent coverage of projects costing more than $100 million.

The Coalition introduced rules requiring all infrastructure and information communication technology projects that draw on state government funding and cost more than $100 million to be subject to a High Value High Risk review by the Treasury.

Under the “Gateway Process”, investment requires business cases to be reviewed before the Treasurer’s approval for funding.

But $24 billion worth of the government’s $27 billion infrastructure agenda has not progressed through the HVHR process, the Auditor-General says, despite being listed in the budget papers as HVHR projects.

Treasurer Michael O’Brien said the major projects outlined in the budget would go through HVHR process.

“We identified projects worth billions of dollars that are not following the standard HVHR process of having a DTF-reviewed and Treasurer-approved business case before being considered for funding,’’ Mr Doyle said.

“These include major road and rail projects, funded as part of the government’s 2014 election commitments, and projects funded as unsolicited bids.”

Treasury says it will apply “a tailored” assessment to these major projects to enable project risks to be considered while supporting accelerated time frames – that process is yet to be defined.

“Given the significance and scale of these projects it is critical that DTF determine how it will effectively apply the HVHR process within these truncated timelines to ensure that the project costs, benefits and timelines have been robustly determined,’’ Mr Doyle said.

The report says it is also unclear how the process will be applied to unsolicited bids, such as the widening of the Tullamarine Freeway.

As part of the audit tabled in Parliament on Thursday Mr Doyle looked at five separate projects, and expressed concern that the current review process by Treasury lacked substantive analysis of project benefits.

“It raises the risk of government investing substantial sums in projects without understanding whether the projected benefits are well founded or achievable,’’ he said.

Mr O’Brien said the government had accepted the recommendations to improve the process, and noted it was the Coalition government that introduced the HVHR process following multibillion-dollar blowouts under Labor’s reign, including the desalination plant and myki.

“Projects announced as part of our record $27 billion infrastructure program will also be subject to these recommendations, to deliver the maximum benefits for Victorian taxpayers,” Mr O’Brien said.

“Labor had 11 years to introduce a process that would have avoided costly mistakes such as myki, desal and the north-south pipeline and failed to do so.”

He also said the Auditor-General had confirmed that the HVHR process provided for greater rigour and scrutiny in the delivery of major projects, ensuring value for money for Victorian taxpayers.

Labor finance spokesman Robin Scott said the Napthine government’s infrastructure plan for Victoria appeared to be written on the back of a napkin.

“The public has a right to be angry that the government is too reckless and dysfunctional to follow its own rules about how taxpayer dollars should be spent,’’ Mr Scott said.

“Generations of Victorians risk suffering the consequences of Denis Napthine’s blind panic.”