By F. Brinley Bruton, Staff Writer, NBC News

HONG KONG (NBC) - Edward Snowden, a former contractor for the National Security Agency charged with espionage, was allowed to leave Hong Kong on Sunday because the U.S. extradition request did not comply with the law, the Hong Kong government said.

"Mr Edward Snowden left Hong Kong today (June 23) on his own accord for a third country through a lawful and normal channel," the government said in a statement.

A statement did not identify the country, but the South China Morning Post newspaper earlier reported that Snowden had left on a flight for Moscow. Snowden has talked of seeking asylum in Iceland.

Meanwhile, WikiLeaks, the whistle-blowing group led by Julian Assange, said it was helping Snowdwn gain political asylum in a "democratic country." The organization also said it had arranged Snowden's "safe exit from Hong Kong" and that he was being accompanied by Wikileaks legal advisers.

The U.S. citizen fled to the Chinese city-region earlier this month in an attempt to avoid prosecution for leaking classified information about NSA surveillance programs, according to his interviews with The Guardian newspaper.

Documents previously leaked by Snowden revealed that the NSA has access to vast amounts of internet data such as emails, chat rooms and video from large companies, including Facebook and Google, under a government program known as Prism.

U.S. officials have charged Snowden with theft of U.S.government property, unauthorized communication of national defense information and willful communication of classified communications intelligence to an unauthorized person.   

The statement from Hong Kong's government added:

Since the documents provided by the US Government did not fully comply with the legal requirements under Hong Kong law, the (Hong Kong Special Administrative Region) Government has requested the US Government to provide additional information so that the Department of Justice could consider whether the US Government's request can meet the relevant legal conditions. As the HKSAR Government has yet to have sufficient information to process the request for provisional warrant of arrest, there is no legal basis to restrict Mr Snowden from leaving Hong Kong.

Officials also said the government of Hong Kong had asked the United States to explain reports it had hacked into Hong Kong computer systems.

Few people in Hong Kong take seriously the accusations from some in the U.S. that Snowden is a Chinese spy.  But he fled to Chinese sovereign territory and Beijing is no doubt taking a close interest, even if it is unlikely to overtly intervene.

Hong Kong was a British colony until it was returned to China in 1997. Under what is known as the "Basic Law" – the territory's mini-constitution – it has a well-respected and autonomous legal system based on British common law, with far stronger protections for human rights and freedom of expression than exists on the mainland.

NBC News' Anna Nemtsova and Albina Kovalyova and The Associated Press contributed to this report.