A massive leak of documents on India’s new military submarines from French shipbuilder DCNS is the result of a hack, the country's defence minister said on Wednesday.

Manohar Parrikar claimed, according to local reports, that the entire designs of its Scorpene submarines hadn't been disclosed. “First step is to identify if its related to us, and anyway its not all 100 percent leak,” he was quoted as saying.

The documents were made public by The Australian on Tuesday, which described the breach as an “Edward Snowden-sized leak.”

A DCNS spokesperson told Ars: “DCNS has been made aware of articles published in the Australian press related to the leakage of sensitive data about Indian Scorpene. This serious matter is thoroughly investigated by the proper French national authorities for defence security. This investigation will determine the exact nature of the leaked documents, the potential damages to DCNS customers as well as the responsibilities for this leakage.”

Although the 22,000-page cache of documents date from 2011, they give very detailed technical information about the combat capability of the Scorpene vessels, which are currently in use in Malaysia and Chile. India signed the £2.6 billion deal for six of the boats in 2005—they are to be built in conjunction with an Indian government-owned Mumbai shipbuilder—and Brazil is due to deploy the vessels in 2018.

Such sensitive information in the wrong hands would have huge ramifications for national security in all four countries. “It appears that the source of leak is from overseas and not in India,” Parrikar said, vowing to investigate further.

Australia is also very concerned. Earlier this year, DCNS won an AUS$50 billion contract—the country’s largest-ever defence deal—to build a new submarine fleet. The French group saw off bids from Germany’s ThyssenKrupp AG and a Japanese-government consortium of Mitsubishi Heavy Industries and Kawasaki Heavy Industries.

Details about the Australian contract, expected to run into the 2050s, weren't disclosed in the leak. But it has raised concerns about the data security of the defence project. The country's prime minister Malcolm Turnbull said the leak was a reminder of the importance of cyber security, but claimed that Australia, where the 4,500-tonne Shortfin Barracuda submarines will be built, has “high security standards”—an assertion called into question in the recent census debacle.