Victoria's opposition is calling for investigations into a $2.3 billion government contract awarded to a China-linked consortium that may use forced labour.
In 2016, Premier Daniel Andrews awarded a contract to build 65 new high-capacity Metro trains to the Evolution Rail consortium, which includes Chinese state-owned firm CRRC Changchun Railway Vehicles, Downer Group and Plenary Group.
The CRRC has since been flagged by the US Defence Department as a national security risk, while the US Department of Commerce blacklisted its supplier KTK Group over links to forced Uighur labour.
Opposition spokesman David Davis has asked the Auditor-General to investigate the project.
Mr Davis said the trains are two years behind schedule and riddled with technical problems.
"Labor has botched its contract with the Chinese Communist owned company CRRC Changchun from the start," he said in a statement to AAP.
"The Auditor-General has the power to pull back Labor's veil of secrecy over the financial mismanagement of this $2.3 billion contract."
Mr Davis has also referred the deal to the state's corruption watchdog, the Independent Broad-based Anti-corruption Commission.
It follows a report by The Age that a person who was formerly employed as a contractor by consortium member Downer, returned to work there shortly after holding a top role in the Victorian government's tender process.
"It's important that the proper authorities, such as IBAC, have the opportunity to investigate concerns over the probity of these multi-billion dollar contracts," Mr Davis said.
The premier on Monday said he had assurances that CRRC was not exploiting workers from the country's Uighur minority.
"We don't agree with everything that's done in every country around the world. But ultimately, we are about getting things done," Mr Andrews said.
"We have sought assurances that it is not an accurate statement in relation to the work we have contracted them to do and have received those assurances."
Mr Andrews noted the NSW government had engaged CRRC to deliver its Waratah trains in Sydney.
More than a million people, including members of the Uighur ethnic minority group, are believed to be detained across China in forced labour camps.