Maintenance of Collins Class submarines could disappear from Adelaide shipyards by 2024, impacting hundreds of businesses and jobs in the state, Freedom of Information (FOI) documents have revealed.

Key points: Senator Rex Patrick says the documents show maintenance will not be done in Adelaide after 2024

Senator Rex Patrick says the documents show maintenance will not be done in Adelaide after 2024 He believes the plan could derail planning and construction of the submarines

He believes the plan could derail planning and construction of the submarines He says if maintenance stays in Adelaide the shipyard will have to be redesigned

The documents provided by Centre Alliance senator Rex Patrick include a letter from Rear Admiral Greg Sammut of the Royal Australian Navy to Naval Group executive director Jean-Michel Billig.

The letter includes instructions for the shipyards in Osborne, which is currently used to maintain the fleet, to be designed without Adelaide playing a role in future submarine maintenance work beyond 2024.

About 700 submarine maintenance jobs remain in limbo in Adelaide with Federal Defence Minister Linda Reynolds yet to make a decision on whether full-cycle docking maintenance work will stay in Adelaide or relocate to Western Australia.

Senator Patrick said he believed the plan could derail the new fleet's planning and construction schedule and a decision on where the fleet should be maintained was one for the Federal Government, not the Navy.

"That's the assumption that has been made by the Navy. They've proceeded on that basis and they should not have," he told the ABC.

"The Admiral in charge of the program has gone well beyond his brief.

"He did not seek or get approval from Cabinet in respect of where future full-cycle dockings will take place.

"There's more than 700 jobs [and] 800 businesses that will be affected, $400 million of activity here in South Australia."

Defence Minister Linda Reynolds is yet to decide whether full-cycle docking maintenance work will stay in SA. ( ABC News: Matt Roberts )

However, WA Defence Issues Minister Paul Papalia said he did not think the letter meant the work was necessarily heading west.

Mr Papalia accused Senator Patrick of playing political games on the issue.

"Senator Patrick will do what he does," he said.

"He's a crossbencher, he's just self-interested and making a case trying to get himself some attention. What we're doing is making the case for Western Australia in the national interest.

"We believe we've got a strong case for bringing full submarine maintenance to Western Australia, where the submarines are based."

Senator Rex Patrick provided FOI documents to the ABC. ( ABC News: Tamara Penniket )

An interim report commissioned by shipbuilder ASC earlier this year revealed that relocating submarine maintenance to WA would likely cost more, see half of the South Australian shipbuilding workforce lose their jobs and reduce safety performance.

ASC has shipbuilding yards in both South Australia and Western Australia and is responsible for the maintenance of Collins Class submarines.

Last month, Mr Papalia questioned the credibility of the report.

"There are challenges associated with leaving it in South Australia," he said.

"In 2024, South Australia will be incapable of meeting the demands for a skilled workforce in the range of 15,000 additional people — they just don't have the capacity."

'Submarine yard will have to be redesigned'

Senator Patrick said the new FOI documents obtained this week showed a diagram of the Osborne site which did not include an area for full-cycle dockings of the Collins Class fleet after 2024.

"The diagram shows that the future submarine construction yard has been designed to completely replace ASC, which is where we currently do the Collins Class full-cycle dockings," he said.

He said if the Government did decide to keep full-cycle dockings in Adelaide, it could now cost taxpayers millions of dollars to redesign the shipyard.

"It's clear that Naval Group has been instructed by the Navy to assume that Collins full-cycle dockings would not be staying in Adelaide after 2024 and that they would build the shipyard using that assumption," he said.

"If the Government decides … to retain full-cycle dockings here in Adelaide, then the submarine yard will have to be redesigned and that will take time and money.

"In my very strong view after 2024 we should still be doing Collins Class full-cycle dockings here in Adelaide and we should be building the future submarines.

"There is enough room at Osborne to do that and the Government needs to be skilling up to make sure there is enough skilled workers to be able to complete both tasks simultaneously."

In a statement, the Department of Defence said the design of the submarine construction yard has not been finalised, and that it was "premature and irresponsible" to suggest a final decision had been made.

"The layout reflected in the documents released is only one option and is still under consideration," a spokesperson said.

"One of the assumptions that was used to allow planning to progress, was that land currently occupied by ASC Submarines would be made available to Naval Group from 2024 to allow for further development of the submarine construction yard.

"This design assumption does not mean that the full-cycle docking will be moving interstate."

In a statement, SA Premier Steven Marshall said the State Government would do all it could to ensure there was enough room at the Osborne site for both ASC and Naval Group.

"We will ensure the Commonwealth has all the land it needs for ASC and Naval Group to coexist at Osborne," Mr Marshall said.

The ABC has contacted Defence Minister Linda Reynolds for comment.