The French company building Australia's new submarines says it was not aware of a major security breach until it was in the media.

Key points: DCNS says it became aware of a major breach via a report by The Australian

DCNS says it became aware of a major breach via a report by The Australian Christopher Pyne attacks Nick Xenophon, accusing him of "playing politics" over the leak

Christopher Pyne attacks Nick Xenophon, accusing him of "playing politics" over the leak An investigation is now underway into the incident

Defence Industry Minister Christopher Pyne has also criticised crossbench Senator Nick Xenophon, accusing him of "playing politics" over the leak.

Mr Pyne said it is alleged details of DCNS's new submarine program for India were stolen by a former employee, with the documents then finding their way into the hands of a staffer for Senator Xenophon.

An investigation is now underway, after the details were later published in The Australian newspaper.

Mr Pyne, who has visited the company's shipyard in France, said he was confident security is up to scratch, during a testy press conference with Australian reporters in Cherbourg.

"Well I hope you haven't flown all the way to Cherbourg to have a fight," Mr Pyne said, as he attempted to divert questions away from DCNS chief executive Herve Guillou.

"Mr Herve is not here to be a punching bag for the Australian press."

Mr Guillou said an investigation is now underway, but that it was ultimately up to the French Justice Department to determine what happened.

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He conceded the company, which was awarded a $50 billion contract to build Australia's submarines, was made aware of the breach "when it was published in the newspapers".

"We have filed a complaint to the French justice department, it's doing its job and then [they will] deliver a conclusion. It's not to me to deliver any conclusion," Mr Guillou said.

Mr Pyne said it appeared a staffer for Senator Xenophon received the plans and was adamant the document should not have been leaked to the media.

"Senator Xenophon wants to play games, he wants to play politics, he wants to cover for the mistake I think he made and his staffer made in not giving DCNS their property back, which is what he should have done," he said.

"What is alleged is a staffer of DCNS stole this information and it came via accident into the hands of a staffer of Senator Xenophon and rather than give that property back, he decided to give it to The Australian.

"If they wanted to assist the Government [and] DCNS they would have [given] DCNS' property back to DCNS, they would have informed the Government."

According to Fairfax Media, Rex Patrick, Senator Xenophon's advisor and former submariner, attempted to inform the Department of Defence about the leak.

Over 22,000 sensitive documents were leaked, detailing the combat capabilities of the Indian submarines, sparking a major diplomatic stoush between France, India and Australia.

Australia will purchase 12 new submarines, which will be built in Adelaide, replacing the ageing Collins Class fleet.

Mr Pyne said the leak from the Indian program had no bearing on the Australian project, because the two countries are building different types of submarines.