More than 22,000 pages of top secret data on the capabilities of six highly advanced submarines being built for the Indian Navy in Mumbai in collaboration with a French company have been leaked, reported the Australian media, raising alarm bells today in the security establishment.

The leaked data reveals stealth capabilities of the Scorpene submarines,  torpedo launch systems, communications and navigation capabilities , frequencies at which intelligence is gathered, noise levels at various speeds, diving depths, range and endurance, magnetic and electro-magnetic data, - all sensitive information that is highly classified.

Since all the documents that emerged in The Australian newspaper were not held by any individual or on a single server in India, some officials believe that the documents may have been leaked through a French source. The report in 'The Australian' suggests that a former French naval officer working as a sub-contractor for the DCNS might be behind the leak of data.

The Scorpene submarine project which is valued at over Rs. 20,000 crore had been at the centre of controversy right from the early stages and the project is already running four years behind schedule.​

As the Scorpene data leak report broke out shaking the Indian defence establishment, French Ambassador Alexandre Ziegler said French authorities were trying to assess the extent, nature and sensitivity of information that may have been leaked.

"Well, I have seen the report in the press. What can I tell you is that the French authorities are taking the matter very very seriously and working very seriously with DCNS, the French ship building company," he told reporters at an event organised at Alliance Francaise here.

Six Scorpene submarines are being built in collaboration with French naval contractor DCNS at a cost of USD 3.5 billion. The data leak has prompted India to order probe into the matter.

"We (French authorities) are trying to assess the extent; the nature, the sensitivity of information that may have been leaked, and we will do work in this... in very very close cooperation (and) with full transparency with Indian authorities," Ziegler said.

Earlier, Defence Minister Manohar Parrikar has said the leak of documents detailing the secret combat capabilities of Scorpene-class submarines was a case of hacking.

Parrikar also has ordered Navy Chief Admiral Sunil Lamba to go into the entire issue and sought a report from DCNS.