The audit office has revealed it has not fully investigated the fund central to the Coalition's multimillion dollar commuter car park scandal.
On Thursday, the Australian National Audit Office told a senate inquiry its investigation into the misappropriation of taxpayers' money through the Urban Congestion Fund solely looked at commuter car park grants.
However it flagged the canvassing implemented by the federal government was the same process for other projects accessing the $4 billion fund.
It was also revealed during the inquiry the department at the centre of the scandal sought legal advice after the ANAO requested ministerial briefings from then infrastructure minister Alan Tudge.
The ANAO previously unveiled Mr Tudge's office created a spreadsheet to target marginal seats with commuter car park funding ahead of the 2019 election.
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Labor senator Tim Ayers probed deputy auditor general Brian Boyd about the surveillance of the fund, which he responded by saying the audit was only applicable to the $660 million car park grant offered by the Coalition.
"We can see that it was the same process being employed, but what we haven't done is actually look at the detail of how it was applied to the non carpark projects," Mr Boyd said.
The ANAO report found the allocation of commuter car park projects were not demonstrated to be on a merit basis, with 83 per cent of grants going to coalition or targeted marginal seats.
Mr Tudge has previously denied any knowledge of the list apparently made by his office.
The ANAO said the issues raised in the report were breaches it found against the current framework. Around $890 million within the UCF has not yet been allocated.
Deputy Auditor General Rona Mellor also said the ANAO has no knowledge of the engagement the department of infrastructure in canvassing other projects through the UCF.
Labor leader Anthony Albanese slammed the Morrison government over the scandal , claiming it a prime example to implement a federal integrity commission.
"It's a disgrace," he said. "And the fact is that's why we need a national anti-corruption commission to stamp out this sort of abuse of taxpayer funds. And with commuter car parks, you have a range of them that they've now abandoned that can't be built because there's no space for them."
During senate estimates it was revealed the funding for the commuter car parks scheme was allocated the night before the federal government entered caretaker mode at the last election.
Labor senator Katy Gallagher in October said: "the colour-coded spreadsheets and maps prove it - and ministers, like minister Tudge, are rewarded for funnelling money into Coalition seats or target seats".
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