Representatives from Ernst & Young were grilled at a Senate inquiry on Monday into Australia's preparedness to host the 2026 Commonwealth and 2032 Olympic and Paralympic Games.
The Victorian government commissioned the consultancy in 2021 to work on the business case to host the Games across regional hubs, which spat out an estimated cost of between $2.5 billion to $3 billion.
An update from July, which was used to justify axing the Games and did not involve Ernst & Young, revised the price tag to $6.8 billion.
EY partners Dean Yates and Leigh Walker repeatedly refused to answer questions from committee members, including how much the firm was paid to develop the original document.
Victorian Liberal senator Sarah Henderson accused the officials of blatantly breaching Senate rules when pressing for an explanation on an expected contribution of $200 million from the federal government, stated in the business case.
Mr Yates said the firm took the assumption at "face value" and Ms Walker declined to confirm its underlying basis, saying it could reveal confidential cabinet information.
"That's just rubbish," Ms Henderson replied.
No federal cash was set aside for the 2026 Games but Treasurer Tim Pallas had been seeking a matching contribution.
Mr Andrews last week conceded the original business case was "hardly the greatest piece of work ever done" but the firm was content with its role in it.
"We stand by the work we did to assist with the development of the business case," Mr Yates said.
The Victorian government this month agreed to pay Commonwealth Games bodies $380 million in compensation after protracted negotiations.
All parties were legally bound not to speak further on the settlement details under its terms.
Under questioning from Nationals senator Bridget McKenzie, Commonwealth Games Australia president Ben Houston said the sports body didn't request the confidentiality clause.
"We didn't ask for it," Mr Houston said.
Senior Victorian minister Ben Carroll attempted to deflect when asked about the claim, saying the state government remained focused on everyday Victorians.
"I'll let 'Sports Rorts' McKenzie get on with her inquiry," he told reporters.
The confidentiality clause included how much was spent by parties to negotiate the settlement, Mr Houston said.
The state government flew lawyers to London to break the news of the cancellation to the Commonwealth Games Federation.
They remained abroad for settlement negotiations for several days, before returning to Australia to continue talks remotely.
CGA chief executive officer Craig Phillips said Games leaders were made aware of some budget pressures for the regional Victorian event as far back as April 18, before the May state budget was released.
"We were involved in some discussions around some measures to actually reduce those costs," he said.
The Senate inquiry, which was reopened following Victoria's decision, could not compel Mr Andrews and former Commonwealth Games delivery minister Jacinta Allan to appear.
Former Victorian sports minister Martin Pakula and Gold Coast Mayor Tom Tate are scheduled to front the inquiry on Monday afternoon.
