"The department of justice is in the initial stages of an investigation into the unauthorised disclosure of classified information by an individual with authorised access," said Nanda Chitre, the justice department spokeswoman.
"Consistent with long standing department policy and procedure and in order to protect the integrity of the investigation, we must decline further comment," Chitre said.
The US statement came hours after British newspaper The Guardian released a video interview with Edward Snowden, a 29-year-old who claimed responsibility for being the source of the information about the secret intelligence practices of the national security agency of the US.
Snowden said he leaked the information because he disagreed with the agency's surveillance practices. "I do not want to live in a world where everything I do and say is recorded," he told The Guardian newspaper.
He is a former technical assistant for the Central Investigation Agency and has been working at the NSA for the past four years as an employee of various outside contractors, the paper reported.
The office of director of national intelligence on Sunday said it is currently assessing the damage that has been caused to the national security by this leak.
"The intelligence community is currently reviewing the damage that has been done by these recent disclosures. Any person who has a security clearance knows that he or she has an obligation to protect classified information and abide by the law," said Shawn Turner, director of public affairs, office of the director of national intelligence.
"We have seen the latest report from The Guardian that identifies an individual claiming to have disclosed information about highly classified intelligence programs in recent days," he said. Snowden is currently in Hong Kong and in his interview said he hoped to receive asylum.
"The only thing I can do is sit here and hope the Hong Kong government does not deport me," he said. A top American lawmaker on Sunday demanded that Snowden be prosecuted and said no country should grant him asylum. "The US must make it clear that no country should be granting this individual asylum," Republican Congressman Peter King said.
The Washington Post said Snowden, a tech specialist who has contracted for the NSA and works for the consulting firm Booz Allen Hamilton.
"Allowing the US government to intimidate its people with threats of retaliation for revealing wrongdoing is contrary to the public interest," Snowden said. In an interview to The Washington Post, he alleged that
US President Barack Obama has failed in his pledge to transparency. He said there was no single event that spurred his decision to leak the information.
"My sole motive is to inform the public as to that which is done in their name and that which is done against them," he said in a note that accompanied the first document he leaked to The Post.
On Sunday, US intelligence chief James Clapper asked the Justice Department to open a criminal investigation into the leaks.
Image: Classified information on secret electronic surveillance programmes to get details of phone calls of US citizens has been leaked | Photograph: Carlo Allegri/Reuters
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