Labor and the Greens have joined forces to disrupt the federal government's agenda in the Senate, forcing a debate on the Perth Freight Link project.
The Greens have long called for the government to release the business case for the controversial Western Australian project, with the Senate ordering the production of the documents six times.
The Senate demanded Finance Minister Mathias Cormann explain why the documents had not been provided.
It forced a debate on the issue that lasted 90 minutes - time that had been allocated to debating legislation aimed at tightening airport security.
Senator Cormann on Tuesday told parliament the government had already provided all the documents it could without harm to the public interest.
The information was either confidential cabinet documents or commercially sensitive.
"Don't come into this chamber and hold up the business of the nation for your ideological little vendettas," Senator Cormann told parliament.
"Just because you're not getting your way."
The federal government has committed $1.2 billion for the Perth Freight Link, including the expansion of Roe Highway.
Senator Cormann said the state and federal governments had bent over backwards to ensure the project was world-leading when it came to environmental standards.
The Perth Freight Link project would save lives and improve productivity while Roe 8 was recognised by Infrastructure Australia as a top infrastructure priority for the nation.
But releasing the business case would do commercial harm to WA, he said.
"The Greens don't like the Perth Freight Link project, we get it.
"The Greens don't like WA going forward."
Greens senator Scott Ludlam said the Senate had to assume the government had something to hide.
The project was announced by former prime minister Tony Abbott without due diligence, he said, claiming the government wouldn't release the documents because the business case didn't stack up.
He also told parliament the project was proceeding "illegally" in violation of a dozen or more environmental conditions.
"I want to know how serious does a breach have to get before (Environment) Minister Josh Frydenberg stops the clock?"
The Roe highway extension project is a key election issue in south Perth, and could affect the outcome of the state election in March.
"This ghost project .. (is) ... a $2 billion zombie that apparently can only be stopped by an election," Senator Ludlam told parliament.
