Transport for NSW has stood by its assessment that the Maldon-Dombarton is not needed now, despite Labor's Anthony Albanese bluntly saying they are "wrong".
Mr Albanese criticised the state government for claiming the freight line is not yet needed.
"They are wrong," Mr Albanese said, "and they should talk to their own department, because their own department in reports that have been leaked indicate that they're wrong."
A Transport for NSW spokeswoman said the line wasn't needed for at least the next decade.
"Future Transport 2056 identifies the Maldon-Dombarton rail link as an initiative for investigation over the next 10 to 20 years, which is also supported by the NSW Freight and Ports Plan 2019-2023," the spokeswoman said.
"This timing is based on analysis of when demand on the network would make completion of the link economically viable."
The spokeswoman also said the rail link was "important" in achieving a "longer term" objective of separating passenger and freight rail services.
Mr Albanese also claimed the government should be taking advantage of the private sector interest in building the line, which he said was there.
"It's been very clear that the proponents of this project want to get ahead and get it done," Mr Albanese said.
However, the government had made attempts to gauge private sector interest in building the line four years ago.
Transport for NSW admitted the cost of the project would likely need heavy private sector investment.
"The business case identified that completing the link would take substantial investment - $805 million in 2014 dollars," she said.