A former contractor for the US National Security Agency, charged by the United States with espionage, was allowed to leave Hong Kong on Sunday because a US extradition request did not fully comply with the law, the Hong Kong government said.
Edward Snowden left for Moscow on Sunday and his final destination may be Ecuador or Iceland, the South China Morning Post said, a move that is bound to infuriate Washington.
US authorities have charged Snowden with theft of US government property, unauthorised communication of national defence information and wilful communication of classified communications intelligence to an unauthorised person, with the latter two charges falling under the US Espionage Act.
The United States had asked Hong Kong, a special administrative region (SAR) of China, to send him home.
"The US government earlier on made a request to the HKSAR government for the issue of a provisional warrant of arrest against Mr Snowden," the Hong Kong government said in a statement.
"Since the documents provided by the US government did not fully comply with the legal requirements under Hong Kong law, the HKSAR government has requested the US government to provide additional information ... 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."
Hong Kong, a former British colony, reverted to Chinese rule in 1997.
The South China Morning Post earlier quoted Snowden offering new details about the United States' spy activities, including accusations of US hacking of Chinese mobile telephone companies and targeting China's Tsinghua University.
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 programme known as Prism.