High-speed rail between Melbourne and Brisbane is "very ambitious", Prime Minister Scott Morrison says, talking down the likelihood of such a project.
However, Mr Morrison made the comments after earlier indicating details of a regional fast rail project would be revealed in the April 2 budget.
"A Melbourne-to-Brisbane fast rail link is a very ambitious program," he told reporters in Melbourne on Thursday.
"We're focusing on projects that we know are going to make a big difference to people right here and now."
Mr Morrison lauded his government's road and rail projects, including the Melbourne airport rail link as well as a rail link for the new Sydney airport.
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But on Wednesday a "fast rail" project involving links between Melbourne and Shepparton, Sydney and Newcastle and Brisbane and the Sunshine Coast formed part of a population plan released by Mr Morrison.
The opposition has long-pushed for the development of a high-speed rail network across Australia.
In 2013 the former federal Labor government published a detailed feasibility study which found a line between Brisbane and Melbourne via Sydney and Canberra would produce $2 of public benefit for every $1 invested.
"The wherewithal to do that and the time frames around that, I think the opposition should be very clear about," the prime minister said.
