The former CIA employee responsible for leaking details of classified U.S. surveillance programmes checked out on Tuesday from a Hong Kong hotel as U.S. authorities weighed criminal prosecution strategies against him.

Edward Snowden has been the focus of media reports since he identified himself as the source who gave newspapers in Britain and the United States classified information about a vast government data collection programme.

While U.S. law enforcement officials worked to build a case against him, criticism of the programme he revealed mounted among privacy and civil rights groups, and the first lawsuit was filed over last week’s revelations.

Mr. Snowden, 29, was believed to be still in Hong Kong on Tuesday, but his whereabouts were unknown. He has expressed interest in seeking asylum in Iceland, but Icelandic Interior Ministry spokesman Johannes Tomasson said there had been no contact with him.

A computer specialist who worked for U.S. government contractor Booz Allen Hamilton, Mr. Snowden had a security clearance giving him access to secret information. The consultancy said on Tuesday it had fired Mr. Snowden from his 122,000-dollar-a-year job “for violations of the firm’s code of ethics and firm policy.” Mr. Snowden left the U.S. in mid May, before the revelations about the programme were published. U.S. lawmakers have called for his extradition, which would require charges to be filed.

Possible criminal charges against Mr. Snowden are “under discussion,” a federal law enforcement official told USA on Wednesday.

Extraditions typically are processes that can take months or years depending on court challenges.

U.S. State Department spokeswoman Jen Psaki would not say whether the U.S. had made an extradition request or might do so in the future.

Mr. Snowden disclosed information about two secret surveillance programmes run by the National Security Agency (NSA).

One of the surveillance programmes collects communications from large U.S. internet companies to monitor non-U.S. citizens abroad who are suspected in terror investigations. The other disclosure revealed a secret court order authorizing collection of the phone records of U.S. citizens.

The American Civil Liberties Union sued the U.S. government on Tuesday, calling the wholesale surveillance of emails, phone calls and other data by the NSA a violation of the constitution.

The lawsuit in federal court alleges that the NSA’s programme violated rights to free speech and privacy and caused hardship for the organization, which requires confidentiality to conduct its business.

Jameel Jaffer, ACLU deputy legal director, called the programme “the equivalent of requiring every American to file a daily report with the government of every location they visited, every person they talked to on the phone, the time of each call, and the length of every conversation.” The legal challenge came as a coalition of more than 80 privacy groups and technology companies called on Tuesday to end a reported government dragnet of internet traffic, saying the alleged scope of the programme represents “a stunning abuse of our basic rights.” The coalition, called Stop Watching US, includes Internet groups such as the Electronic Frontier Foundation, Mozilla, Reddit and the ACLU. In addition to an open letter to Congress, the groups launched an online petition calling for a congressional investigation into the scope of the telephone and online data collection. “This type of blanket data collection by the government strikes at bedrock American values of freedom and privacy,” the coalition wrote.

“This dragnet surveillance violates the first and fourth amendments of the U.S. Constitution, which protect citizens’ right to speak and associate anonymously and guard against unreasonable searches and seizures that protect their right to privacy.” Google, Facebook and Microsoft, which were among the nine major companies reported to have given the government access to their servers, called for permission to make public more details about government requests for data.

“Assertions in the press that our compliance with these requests gives the U.S. government unfettered access to our users’ data are simply untrue,” Google chief legal officer David Drummond wrote to Attorney General Eric Holder and FBI director Robert Mueller.

“However, government non-disclosure obligations regarding the number of FISA (Foreign Intelligence Surveillance Act) national security requests that Google receives, as well as the number of accounts covered by those requests, fuel that speculation.” Leading members of Congress have criticized Mr. Snowden.

Speaker of the House John Boehner called him a “traitor,” and Peter King, Republican chairman of the House Homeland Security Committee, said Mr. Snowden be should be prosecuted to the fullest extent of the law. “The disclosure of this information puts Americans at risk,” Mr. Boehner told broadcaster ABC. “It shows our adversaries what our capabilities are, and it’s a giant violation of the law.” Dianne Feinstein, a California Democrat and chairwoman of the Senate Intelligence Committee, said the panel would hold a closed briefing on Thursday for all senators to hear from NSA, FBI and Justice Department officials, The New York Times said.

Civil liberties advocates say the surveillance programmes are unacceptable intrusions into privacy, but supporters say they are legal and have yielded evidence that has helped stop terror plots.

A Pew Research Center and Washington Post survey on Monday found that 56 per cent of Americans polled believed the NSA’s phone-tracking programme was an acceptable way to investigate terrorism, while 41 per cent said it was unacceptable.

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