Cross-party political consensus on the ambitious Future Submarines program is beginning to splinter in South Australia, where construction on the $50 billion project is scheduled to begin in 2022.

Four South Australian crossbench senators have attacked the plan to build 12 submarines using French company Naval Group, arguing tens of billions could be saved and technical risks reduced if a different international firm was used.

The criticism from Centre Alliance senators Rex Patrick and Stirling Griff, as well as Australian Conservatives founder Cory Bernardi and independent Tim Storer, comes just days after the ABC revealed growing tensions between France's Naval Group and the Australian Government over contract negotiations.

Defence and industry figures have told the ABC France and Australia will not be ready before 2019 to sign a crucial "strategic partnering agreement", which is needed before detailed design contracts can be finalised, and submarine construction begins.

Senator Patrick, who has regularly criticised the decision to choose a French design, said the Future Submarine Project was now "a project out of control".

"With news that the project's cost has now blown out to more than $200 billion, it's time to reassess the program's direction," he said.

Senator Rex Patrick wants the Future Submarines project to be reassessed. ( ABC News: Gary-Jon Lysaght )

Senator Storer warned the Government was, "taking huge gambles on our long-term Defence future and on our ability to fund our defence given other priorities".

"I am concerned about the submarines on a number of fronts: the cost blowout versus the off-the-shelf alternatives, the choice of technology being made, the delay in getting them built and in service, and the consequent risk to Australia's continental security," he said.

But Defence Minister Christopher Pyne rejected the criticisms and suggested South Australian voters would not look kindly at the comments.

"The idea that we could scrap that when so much work has already been done on it and so much money spent on it is quite frankly fanciful," Mr Pyne told Radio National.

"I hope the voters of South Australia remember that senators Storer, Patrick and Bernardi have called for the scrapping of the largest investment by the Commonwealth Government in any state since federation."

Pyne 'meeting with everyone who needs to be talked to'

Mr Pyne also rejected suggestions he had refused to meet senior officials from Naval Group when they flew to Adelaide.

"The ABC story that I refused to meet with the French is completely false," Mr Pyne said.

"I'm not the chief negotiator, we have a negotiating team in the Department of Defence and commercial support for that negotiating team … but of course I am meeting with everyone who needs to be talked to about these matters because that's part of my job."

Federal Opposition sources have suggested that if a strategic partnering agreement is not signed before next year's election, Labor could review the Future Submarines project if it wins office.

But Shadow Defence Minister Richard Marles insisted Labor remained committed to the current French-designed submarines.

"I look forward to a future Labor government delivering this project in partnership with the French Government and Naval Group," Mr Marles said.

"It's important the Government negotiates a strategic partnership agreement that reflects our national interest and gets it signed so that, as a country, we can get on with this project."