Leaked plans for a new submarine fleet destined for the Indian navy have provoked a flurry of investigations and speculation Wednesday about how the classified information came to light.
Details of the submarines, being made in France by defence firm DCNS at a cost of some 3 billion dollars, first appeared in the Australian press.
Australia recently commissioned DCNS to build its own new fleet of submarines, and the leak of over 22,000 pages of documents has raised concerns there about the security of the deal.
"I understand there has been a case of hacking," Indian Defence Minister Manohar Parrikar told reporters. "We will find out what has happened," he was quoted as saying by The Times of India.
Documents reproduced in the press apparently showed which radio frequencies the submarines use, how loud they are, among other specifications.
DCNS confirmed the "serious" leak and said national authorities had started an investigation.
The leak had "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 firm was quoted as saying.
The Indian Defence Ministry suggested that the leak had come from overseas.
The journalist in The Australian newspaper who broke the story, Cameron Stewart, told The Hindu: "I do not believe that the leak came from India, but it came from France."