French authorities will investigate the leak of thousands of pages of sensitive submarine documents by the French shipbuilder selected to help design and build Australia's next fleet of 12 boats.

The Australian reported on Wednesday that the more than 22,000 leaked pages of documents detail combat capability of six Indian Scorpene-class submarines designed by French shipbuilder DCNS.

The data was reportedly written in France for the Indian project in 2011 and is suspected of being removed by a former French Navy officer who was a DCNS subcontractor. It was reportedly taken to a south-east Asian company and then to an Australian firm.

"As a serious matter pertaining to the Indian Scorpene program, French national authorities for Defence security will formally investigate and determine the exact nature of the leaked documents," a spokesperson for DCNS said in a statement.