The Victorian Opposition has continued to defend the decision to sign the contracts for the East West Link before the November 2014 election, despite scathing criticism from the state's auditor-general

In a report to Parliament tabled on Wednesday, Dr Peter Frost said it cost the Andrews Labor Government $1.1 billion to cancel the deal.

He criticised both sides of politics for wasting taxpayers' money.

The auditor-general said the former Napthine government's decision to sign the contract at that time was "disproportionately aimed at achieving contract execution prior to the 2014 state election rather than being in the best interests of the project or use of taxpayers' money".

Michael O'Brien, who was the treasurer under the previous government, continued to defend the decision, despite knowing Labor would cancel the project.

Mr O'Brien said his government was obliged to go ahead with the deal after an 18-month tender process.

"When you have a tender process, you're obliged to follow it through," he told 774 ABC Melbourne.

"Governments sign contracts outside caretaker [mode] all the time and subsequent governments are bound by it.

"It would've been a huge embarrassment to the state of Victoria [if we'd cancelled].

"You have financiers who are part of the tendering process, there's money being secured, and once we announced a preferred tender those financial arrangements were being put in place.

"It would have exposed the state to damages if we prolonged the tender process."

The Opposition had earlier said they would revive the East West Link during the next election campaign.

"The need to join up the Eastern Freeway and CityLink remains. We want to make sure there's money to pay for our projects," Mr O'Brien said.

The auditor-general said the billion-dollar cost of cancelling the project would be partially offset by the sale of properties acquired for the project, at an estimated $320 million.

The project was meant to include an 18-kilometre road connecting major arterials - the Eastern Freeway at Hoddle Street to CityLink, the Port of Melbourne and on to the Western Ring Road.