A potential extradition tussle in Hong Kong over an American who has exposed the U.S. government's top-secret surveillance programs could prove to be a test case for civil liberties in the financial hub controlled by China.

Edward Snowden, 29, a contractor at the National Security Agency (NSA), chose Hong Kong as the international bolt-hole from where to leak details of the programs, endorsing the city for its "spirited commitment to free speech and the right to political dissent".

Since the former British colony's return to Chinese rule in 1997, however, the city's pro-democracy politicians and activists have complained that Beijing has been steadily eroding Hong Kong's freedoms despite constitutional safeguards granting a high degree of autonomy.

Packs of reporters continued to stake out hotels across the city on Tuesday but Snowden remained out of sight, a day after he checked out of a luxury hotel in the Kowloon district.

Ewen MacAskill, a Guardian journalist who has been in close touch with Snowden in Hong Kong said he had no immediate plans to leave the territory and could be gearing up for a legal fight.

"I'd imagine there's now going to be a real battle between Washington and Beijing and civil rights groups as to his future," MacAskill told Reuters.

"They (the United States) could have taken all sorts of actions against him. Now it looks like the only one available to them is an extradition request," he added, declining to give any details of Snowden's movements or whereabouts.

In talking up Hong Kong's autonomies and freedoms, Snowden has raised the political stakes should Washington make a formal extradition request, a process that could drag out for months in court.

Hong Kong has a long-standing extradition agreement with the United States that has been exercised on numerous occasions since 1998.

Snowden could challenge any U.S. extradition request, and also make a claim for political asylum, a course of action that typically takes months, if not years.

For the moment, he has a 90-day visa which has about two more months to run. He could seek an extension, with the Hong Kong government having the right of refusal.

Legal sources in Hong Kong said Snowden would likely seek representation with lawyers in the city, including two of the most prominent, Philip Dykes and Mark Daly, who have offered free legal services for high profile cases in the past.

Dykes, who has worked on extradition and human rights cases, declined to confirm or deny whether he had been approached by Snowden.

Daly, speaking by telephone from Geneva, said he wasn't aware of any approach by Snowden, but said he would be willing to represent him if asked.

MUTED CHINA RESPONSE

China, so far, hasn't publicly commented on Snowden's case given a three-day public holiday this week. Media coverage of the controversy has also been muted, with the official People's Daily newspaper carrying a headline "National security meets personal privacy, US government's secret surveillance scheme has intrigued discussion."

Hong Kong's left-leaning Wen Wei Po newspaper described Snowden as a whistle-blower with an "American conscience".

Comments on China's Weibo microblogging service referring to Snowden were not censored.

"He is an honest man and a fighter and a real American," wrote one microblogger named Mingdao Jijin. "The era of the United States being able to control others but not itself is over."

Under the extradition agreement, Hong Kong's leader has the right to refuse the surrender of a person to the United States if it relates to the "defense, foreign affairs or essential public interest."

Despite Snowden's value to China as a potential trove of U.S. intelligence, any moves by China to veto a U.S. extradition request could cause serious damage to U.S.-China relations just after a successful summit between President Barack Obama and Chinese President Xi Jinping in California.

"From a foreign policy perspective, I don't think China would block anything like that. It wouldn't look good," said David Zweig, a Hong Kong-based expert in Chinese politics.