Federal Infrastructure Minister Catherine King has reaffirmed her focus on building high-speed rail between Sydney and Newcastle first, saying she believes a new business case would back the route.
Ms King acknowledged enthusiasm for a link between Canberra and Sydney or Sydney and Melbourne, but her comments will dampen hope of fast improvements to the train line into the capital.
Ms King said she was determined to see a broad high-speed rail project built, but a new business case would be prepared by the government's new high-speed rail authority.
"Of course we want to build the entirety of it, but you have to start. And the start has to be Sydney to Newcastle," Ms King said in an address to the National Press Club on Wednesday.
"I'm very focused on the Sydney to Newcastle bit because I think that is where the business case will stack up, but we have to do the work," she said.
"You have to start and that's really what the legislation and recruiting a new board and a new chair to this organisation is all about."
Ms King said a previous business case for high-speed rail on the east coast, released a decade ago, had demonstrated it was most viable to start in areas which already had commuter demand for services.
The federal government last Friday announced it was searching for board members for its high-speed rail authority, which was established in legislation last year.
Ms King said the government would ask the new authority to work closely with Infrastructure Australia to work out how high-speed rail would be funded in Australia.
Infrastructure Australia had in 2020 identified the Canberra-to-Sydney rail corridor as an urgent priority, saying it needed to be improved in the next half a decade.
Chief Minister Andrew Barr has said it would be a "game changer" to improve the current alignment to cut journey times between Canberra and Sydney to three hours, making it competitive with driving.
Mr Barr told The Guardian last week if the connection between Sydney and Newcastle proved to be too complex, work should shift to the Canberra link, which he said required more straightforward improvements.
A report by UK rail expert Professor Andrew McNaughton, commissioned by the NSW government but never publicly released, recommended the state prioritise high-speed rail between Wollongong and Newcastle, with a connection to Canberra not a top priority, The Sydney Morning Herald reported in December.