The review was not able "to form a view on whether the project is a worthwhile and prudent investment … for the NSW government".
The audit also found there to date had not been enough independent monitoring of the concept, business case and tendering for the signature infrastructure project, which is to form a 33 km toll road through inner Sydney.
Non-compliance with own Framework
Only one review tracked the project in its early stages, however if the government had followed its own Major Projects Assurance Framework, then four more would have occurred, according to the report.
The report stated: "The current governance arrangements blur responsibility and accountability for delivery, commissioning and assurance and thereby create a conflict."
NSW shadow minister for roads spokesman Michael Daley said the new report should set off "alarm bells", and the situation was a deeply "embarrassing and disturbing" one for the NSW government to have found themselves in.
"Why won't (Premier) Mike Baird and (Transport Minister) Gladys Berejiklian abide by their own guidelines?" he said.
"This is the supposed to be the most expensive infrastructure project in the nation and the first document, the initial business case, is substandard."
Transparency needed
Greens transport spokesman Mehreen Faruqi called on the Baird government to make the business case public.
"This report raises more than enough questions to warrant a parliamentary inquiry," he said.
"It seems as if in its rush to get shovels on the ground for this wasteful WestConnex toll road, this government has cast aside even basic principles of risk management, independent review and assurance."
NSW Roads Minister Duncan Gay dismissed the major parties' comments saying the government had been compliant.
"We respectfully disagree. We have followed world best practice on procurement and delivery and it complied with the processes set by cabinet," Gay said.
