The proposed rail network would extend as far north as the Wide Bay region and include links to Logan, Gympie, Maryborough and Bundaberg, according to Opposition Leader Tim Nicholls.

Details were scant on Monday morning as the Liberal National Party promised a business case for the Southeast Queensland Very Fast Train network if elected but offered no information on price, time frame or even what technology could be used for the proposal, first flagged in May when Mr Nicholls wrote to the Prime Minister.

Mr Nicholls also left open the door to new technology to power the proposal, such as the vacuum-sealed Hyperloop concept spruiked by charismatic tech billionaire Elon Musk.

"A Very Fast Train network is worth exploring as it would help realise a 30-minute city concept for south-east Queensland," he said, in a statement.

"It would open up job-creating opportunities across the south-east from Bundy to the border.

"This means you could live and play on the Sunshine and Gold coasts, for example, but work in the Brisbane CBD and travel time would be only 30 minutes away."

High-speed rail has been a spectre on Australia's political horizon for decades, with separate plans to link southern capitals dating to the 1980s and Brisbane included in the most recent federal proposal.

The proposals have generally failed to stack up, citing economic concerns over Australia's sparse population.

The federal government has promised to spend $20 million to develop a business case for a high-speed train network linking Sydney, Melbourne, Canberra and Brisbane.

Deputy Opposition Leader Deb Frecklington said the proposal would mean people could live in regional centres and commute to Brisbane while easing congestion on the Pacific Motorway and Bruce Highway.