SYDNEY, Aug 24 (Reuters) - The French shipbuilder which earlier this year won a A$50 billion ($38.06 billion) contract to build Australia’s next generation submarines has suffered a massive data leak, raising doubts about the security of one of the world’s biggest defence projects.

France’s DCNS Group beat out Germany’s ThyssenKrupp AG and a Japanese-government backed bid by Mitsubishi Heavy Industries and Kawasaki Heavy Industries , in a blow to Japanese Prime Minister Shinzo Abe’s push to develop defence export capabilities as part of a more muscular security agenda.

The leak, which was first reported in The Australian newspaper on Wednesday, contains more than 22,000 pages outlining the entire secret combat capability of six submarines that DCNS has designed for the Indian Navy.

The documents cover the Scorpene-class model and do not contain any details of the vessel currently being designed for the Australian fleet, which will be a conventional model based on DCNS’s nuclear-powered Barracuda.

“As a serious matter pertaining to the Indian Scorpene programme, French national authorities for defence security will formally investigate and determine the exact nature of the leaked documents,” a DCNS spokeswoman said in a statement.

“The matters in connection to India have no bearing on the Australian submarine programme which operates under the Australian government’s arrangements for the protection of sensitive data.”

A spokesman for the French embassy in Canberra declined to comment on the leak when reached by Reuters. The Indian High Commision in Canberra could not immediately be reached for comment.

Australian Prime Minister Malcolm Turnbull sought to deflect concerns about the leak, touting the high security standards in place within Australia, where the submarine will be built. The Australian reported that the leak occurred in France in 2011.

“But clearly, it is a reminder that, particularly in this digital world, cyber security is of critical importance,” he told the Seven TV network.

Japan had been seen as early frontrunners for the contract, but its inexperience in global defence deals and an initial reluctance to say it would build in Australia saw it slip behind DCNS and ThyssenKrupp.

Tokyo called the decision “deeply regrettable” and demanded an explanation from Australia of why its bid failed.

The leak comes as Australian Defence Minister Marise Payne announced that she would visit Japan this week for meetings with her Japanese counterpart, Tomomi Inada, the first visit by an Australian defence minister since the winning bid was announced. ($1 = A$1.3) (Reporting by Matt Siegel; Editing by Nick Macfie)