Hong Kong authorities were silent yesterday on the fate of a former US National Security Agency (NSA) contractor ahead of an expected extradition request by the United States where he has been charged with spying.

Hong Kong Police Commissioner Andy Tsang declined to give details but said Hong Kong would deal with the case in accordance with the law.

"The laws that are enforced in Hong Kong are Hong Kong laws, not foreign laws," he said.

The South China Morning Post last night reported exclusively that "contrary to some reports, Edward Snowden is not under police protection but is in a 'safe place' in Hong Kong."

Earlier, the city's Apple Daily newspaper said police had provided Snowden with a safe house and protection. Police had checked his documents to make sure he hadn't overstayed but didn't talk to him on other matters or take any statement, the paper said, citing police sources.

The Post newspaper last night said on its website that it is ready to reveal more explosive details of the US cyber-spying operation against in Hong Kong, China's mainland and the region.

It said documents seen by the Post and statements by Snowden show that Washington's cyber-spying program carried out hacking of major telecommunication companies in China, sustained attacks on network backbones at Tsinghua University and hacking computers at the Hong Kong headquarters at Pacnet, which owns one of the most extensive fibre optic submarine cable networks in the region.

The paper quoted Snowden as saying that the US government is hacking Chinese mobile phone companies to steal millions of text messages. Snowden claims he has the evidence to prove it.

In its disclosure last night, the Post said Tsinghua University, widely regarded as China's top education and research institute, was the target of extensive hacking by US spies this year. In a single day in January, at least 63 computers and servers in Tsinghua were hacked by the NSA.

The paper said its edition today would contain further revelations.

Legal sources in Hong Kong say Snowden has approached prominent lawyers in preparation for a protracted extradition battle.

If Hong Kong authorities don't charge him with an equivalent criminal act, authorities cannot arrest or take legal action. He was also theoretically free to leave the city, one legal expert said.

Simon Young, a law professor at the University of Hong Kong, said a formal extradition request would likely be made through diplomatic channels to Hong Kong's chief executive, who must decide whether or not to issue an "authority to proceed."

Key dates in the case

June 22: The Guardian, quoting documents released by Snowden, says Britain's electronic eavesdropping agency last year was handling 600 million "telephone events" a day.

June 21: Snowden is charged with espionage by US authorities, who ask Hong Kong to arrest him. A day earlier, a businessman linked to WikiLeaks says people in Iceland are preparing a flight to that country for Snowden to take asylum.

June 15: Facebook and Microsoft, aiming for transparency, reveal that in 2012 they received thousands of requests from US authorities for information about customers.

June 10: Snowden leaves the Hong Kong hotel where he had been staying. His whereabouts remain unknown to this day.

June 5: The British newspaper The Guardian reveals the existence of a secret US court order forcing US telephone company Verizon to provide the National Security Agency with daily information on its customers' calls.