The navy, however, stressed that the data in the leaked report is hypothetical, pertaining to simulators, and the signature of a boat can be known only when it hits the seas.
The navy also made it clear that the leak did not take place in India.
The data, which comprises over 22,000 pages, was leaked, the Australian media reported.
It contained documents on the Scorpene submarines, designed by French company DCNS and being built in India by the Mazagaon Dock Limited in Mumbai (Maharashtra) at a cost of around $3.5 billion.
The news created ripples in India soon after the report in the Australian media came out. According to sources, experts from the navy started examining the documents on Tuesday night.
Defence Minister Parrikar, who sought a report in two days, said it appeared to be a case of hacking.
"The first step is to identify if it relates to us," Parrikar told reporters here.
"The navy chief (Admiral Sunil Lanba) has been asked to analyse what exactly has been leaked," the minister said, adding his first assessment was that it was an act of hacking and not a 100 per cent leak.
"I've told the navy chief to find out all the details. Maybe, in a couple of days, I'll be able share with you."
The navy, in a statement issued shortly after the minister spoke, stressed the leak did not happen in India.
"The available information is being examined at the Integrated Headquarters, Ministry of Defence (Navy), and an analysis is being done by the specialists concerned," the navy said.
"It appears that the leak's source is overseas and not in India," the statement said.
A complaint was also filed at the Prime Minister's Office, though there was no official statement from the PMO on the issue.
The Defence Minister was briefed by the navy chief. Later, he also held a meeting with top naval officials.
The opposition Congress alleged that the government was trying to cover up the issue. Former Defence Minister A.K. Antony demanded a probe.
"Despite this blunder, which has hurt our defence preparedness, explanation of Modiji's Defence Minister is that it is a case of hacking. The Indian Navy is saying the leak is possibly from a source outside India. It is intriguing how clean chits are being meted out without looking into the matter," Congress spokesperson Randeep Surjewala said.
Navy sources, meanwhile, maintained there is nothing to be alarmed about as the data does not pertain to any of the Scorpene submarines currently being built in Mazgaon Docks, Mumbai.
"Details in the leaked documents regarding the Scorpene submarine are not valid because the signature can be known only once the boat goes out to the seas," a navy source said, adding the specifications mentioned in the document are hypothetical.
"How can we know the signature of the boat which is still not done with the trials. The technical and operational details will be written by how we exploit the submarine. So far, even the weapon systems and torpedo are not there."
The navy, nonetheless, held the leak is an issue of concern.
"The documents should not have been leaked, but there is nothing to be alarmed about," said the source.
DCNS, two-thirds owned by the French government, said a probe will be carried out to determine the exact nature of the leaked papers, potential damage to the company and customers and responsibilities for this leak.
The Australian media reports, quoting DCNS, said that the leak of such technical data could not happen with its submarine proposed for Australia. The French company also alluded that the leak may have occurred at India, rather than from France.
DCNS this year signed a contract with Australia for the manufacture of 12 submarines.
The first of the Scorpene-class submarines being built in India, Kalvari, went for sea trials in May and is expected to be inducted in the Indian Navy by this year-end.
Officials said the other six submarines, in different stages of construction, will be inducted subsequently at intervals of nine months each.
The variants of the Scorpene submarine are used by Malaysia and Chile, and Brazil is soon to join the club.
