Australia should grab the opportunity of very low interest rates to build the very fast train now along the east coast, according to former trade minister Andrew Robb.
"We have to do it ... we should do it now whilst the world is awash with cheap money," he said.
Mr Robb said three international companies had approached him "again and again" offering to finance and build the line, to link Canberra, Sydney and Melbourne.
He put his frank assessment about the nation-building project two days after announcing he was stepping down from the Turnbull cabinet.
Fairfax Media has received a recording of a speech he gave at a freight symposium at Canberra Airport in which he praises the airport for providing space for a VFT station
"The very fast train would enormously complement what you're got in mind on the aviation front and you've made provision for the arrival point," he said.
Mr Robb oversaw the free trade agreements with China, South Korea and Japan and the signing of the Trans-Pacific Partnership.
He said high speed trains were in operation "everywhere I go".
"There are 200,000 kilometres of very fast train in China – there's not many developed countries in the world that haven't got the advantage of this and we have to do it," he said.
"It's even more important with the distances [in Australia].
"The thing is, we should do it now whilst the world is awash with cheap money – in six or seven years it may not be – but it is at the moment.
"It's awash with nervous investors but they're keen to put their money into long term sustainable projects in safe havens and Australia is seen as a safe haven."
Mr Robb told his high-powered audience he had overseen 80 investment roundtables in 27 countries in the past two-and-a-half years.
"We are very attractive, the interest in Australia is huge – as long as we've got investment-ready projects, we can attract a lot of this money now," he said.
"I can give you [the names of] companies from three nations who been seeing me again and again, they'll do the whole lot, they'll finance the whole lot."
Mr Robb rejected arguments that the VFT would not be viable due to low patronage resulting from Australia's relatively small population.
He said California was opened up by rail barons who did not make money out of patronage.
"They made their money out of value capture," he said, by being given parcels of land around the cities where the rail line would be built.
He said Hong Kong's rapid transit railway system was entirely funded by value capture.
"They work out where the next train line will be and they go and buy the land where the stations will be," he said.
Complexes were built on top of underground stations.
"That's the sort of principle that could apply [here] ... we should grab these opportunities," he said.
Member for Eden-Monaro Peter Hendy is strongly behind the VFT project because of its potential to develop regional Australia.
The Abbott government decided in 2013 to abolish the High Speed Rail Advisory Group but the Turnbull government is continuing to work with the NSW, Victoria, Queensland and ACT governments to protect the identified rail corridors.
In April 2013 the cost of the project was estimated at $114 billion, with the line able to be fully operational by 2065.
In August 1991 the federal cabinet rejected proposed tax breaks which were estimated to cost $1.4 million in 1990 dollars, for the very fast train.
Ministers were told the case presented by the joint venture did not warrant government intervention on the scale sought for the private sector project.