Australian taxpayers are covering the cost of keeping the price of the future submarine project secret.

A French company is fighting to keep secret the original price it quoted for Australia's massive future submarine project, and Defence has confirmed it has joined the appeal, meaning government money is backing the bid too. 

In 2016 French form Naval Group, then known as DCNS, won a competitive evaluation process to design and build 12 new submarines for the Royal Australian Navy.

At the time, the project was allegedly worth $50 billion, though the Commonwealth has more recently put the figure closer to $90 billion.

South Australian Senator Rex Patrick began a Freedom of Information battle in June 2018 to discover what the true, total price was for the contract.

Defence formally blocked the request the first time around, leading Senator Patrick to seek a review by the Information Commissioner.

Australian Information Commissioner Angelene Falk last year found in favour of Senator Patrick, ordering Defence to release details of Naval Group's successful bid.

Defence then appealed Commissioner Falk's decision to the Administrative Appeals Tribunal (AAT), and Naval Group joined the proceedings.

In response to questions posed in March, Defence has confirmed it is covering Naval Group's legal expenses.

Senator Patrick says this is “outrageous” and has prompted questions about the competency of Defence Department Secretary Greg Moriarty.

“The Independent Information Commissioner has determined that the information I am seeking – the price Naval Group offered to sell a fictitious future submarine to Australia for – should be public,” he said. 

“It's concerning that the taxpayer is paying the legal costs of the Defence Department to challenge the Information Commissioner's order to hand over the information.

“It is completely outrageous that the taxpayer is also paying the legal costs for Naval Group, a commercial entity with a 3.3 billion Euro turnover,” Senator Patrick added.

Reports say Naval Group is being represented at the AAT by one barrister and three other lawyers, who are working alongside a barrister and two lawyers from the Australian Government Solicitor's office.

“Defence has advised that it is obliged to pay under the future submarine project's Strategic Partnering Agreement with the Commonwealth,” Senator Patrick said. 

“The Secretary of Defence, the person responsible for all Defence contracting approvals, has been played as a sucker in this, although it is the taxpayer that wears the negative consequences.”