The former contractor, whose work at the National Security Agency gave him access to highly classified U.S. intelligence, made the assertions in an interview with the South China Morning Post. The newspaper said he showed it "unverified documents" describing an extensive U.S. campaign to obtain information from computers in Hong Kong and mainland China.
"We hack network backbones -- like huge Internet routers, basically -- that give us access to the communications of hundreds of thousands of computers without having to hack every single one," he said.
According to Snowden, the NSA has engaged in more than 61,000 hacking operations worldwide, including hundreds aimed at Chinese targets. Among the targets were universities, businesses and public officials.
The interview was the first time Snowden has surfaced publicly since he acknowledged in interviews with The Washington Post and Britain's Guardian newspaper Sunday that he was responsible for disclosing classified documents outlining extensive U.S. surveillance efforts in the United States.
Senior American officials have accused China of hacking into U.S. military and business computers. Snowden's claims of extensive U.S. hacking of Chinese computers tracks assertions made repeatedly by senior Chinese government officials that they are victims of similar cyber-intrusions.
Snowden's claims could not be verified, and U.S. officials did not respond to immediate requests for comment.
In the interview with the Morning Post posted online Wednesday, Snowden said he stood by his decision to seek asylum in Hong Kong, a semiautonomous city, after leaking documents about a high-level U.S. surveillance program.
"People who think I made a mistake in picking Hong Kong as a location misunderstood my intentions," he said. "I am not here to hide from justice; I am here to reveal criminality."
He added, "I have had many opportunities to flee HK, but I would rather stay and fight the United States government in the courts, because I have faith in Hong Kong's rule of law."
By speaking with Hong Kong's oldest English-language newspaper, Snowden seemed to be directly addressing the city he has chosen as his safe harbor. And by disclosing that he possesses documents that he says describe U.S. hacking against China, he appeared to be trying to win support from the Chinese government.
Snowden told the Hong Kong newspaper that he was describing what he says are U.S. cyber attacks on Chinese targets to illustrate "the hypocrisy of the U.S. government when it claims that it does not target civilian infrastructure, unlike its adversaries."
Some in Hong Kong are responding to his campaign. A rally is being organized Saturday to support the 29-year-old former government contractor, who has been in the city since May 20. A website, www.supportsnowden.org, has been set up with details about the event, which will include speeches from human rights activists and local legislators.
Activists in Hong Kong said they admired Snowden's effort to shed light on his government's practices.
"He is a brave man. The authorities cannot use the 'anti-terrorism' excuse to invade people's privacy without boundaries," said Yang Kuang, a prominent Hong Kong activist. "I hope more and more people will stand out and expose such practices."
Snowden said in his interview that he has "been given no reason to doubt ⅛Hong Kong's€ legal system."
"My intention is to ask the courts and people of Hong Kong to decide my fate," Snowden said.
Snowden is up against an extradition treaty between the United States and Hong Kong that many view as being clear - that in the vast majority of cases, Hong Kong must cooperate with U.S. government requests for help apprehending suspected criminals.
The United States has yet to file a formal extradition request, although there are other ways for the governments to be cooperating.
James To Kun-sun, a Hong Kong legislator and solicitor, said that even without an extradition request, the United States can ask Hong Kong law enforcement to watch Snowden while the U.S. Justice Department moves on its investigation. The FBI has a legal attache in Hong Kong, and Snowden has also identified a CIA presence in the city.
"I suspect in this case ... the FBI tells the HK police, 'The request will be very soon,' and they can ask police to keep an eye on him," Kun-sun said.
Once an extradition request is received, a judge in Hong Kong will decide whether it falls under the treaty and whether local law enforcement should help the United States by, for example, collecting evidence or carrying out an arrest. Snowden could also appeal any decision, so the process could be drawn out.
"As long as I am assured a free and fair trial, and asked to appear, that seems reasonable," Snowden said.
He added that he plans to stay in Hong Kong as long as the city will have him.
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