Hong Kong (CNN) -- U.S. intelligence agents have been hacking computer networks around the world for years, apparently targeting fat data pipes that push immense amounts of data around the Internet, NSA leaker Edward Snowden told the South China Morning Post on Wednesday.
Among some 61,000 reported targets of the National Security Agency, Snowden said, are hundreds of computers in China -- which U.S. officials have increasingly criticized as the source of thousands of attacks on U.S. military and commercial networks. China has denied such attacks.
The Morning Post said it had seen documents provided by Snowden but was unable to verify their authenticity. The English-language news agency, which operates in Hong Kong, also said it was unable to independently verify allegations of U.S. hacking of networks in Hong Kong and mainland China since 2009.
Snowden told the paper that some of the targets included the Chinese University of Hong Kong, public officials and students. The documents also "point to hacking activity by the NSA against mainland targets," the newspaper reported.
The claims came just days after U.S. President Barack Obama pressed Chinese President Xi Jinping to address cyberattacks emanating from China that Obama described as "direct theft of United States property."
Snowden's allegations appear to give weight to claims by some Chinese government officials that the country has been a victim of similar hacking efforts coming from the United States.
His claims came as Gen. Keith Alexander, the National Security Agency chief, testified at a U.S. Senate hearing that the country's cyberinfrastructure, including telephones and computer networks, is somewhat vulnerable to attack.
On a scale of one to 10, "our critical infrastructure's preparedness to withstand a destructive cyberattack is about a three, based on my experience," he said.
In the Morning Post interview -- published one week after the British newspaper The Guardian revealed the first leaks attributed to Snowden -- he claimed the agency he once worked for as a contractor typically targets high-bandwidth data lines that connect Internet nodes located around the world.
"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," the newspaper quoted him as saying.
A "backbone" is part of the inner workings of a computer network that links different parts of that network. It is used to deliver data from one part of the network to another and, as such, could expose data from multiple computers if hacked.
'Trying to bully'
Snowden, 29, worked for the Booz Allen Hamilton computer consulting firm until Monday, when he was fired after documents he provided to journalists revealed the existence of secret programs to collect records of domestic telephone calls in the United States and the Internet activity of overseas residents.
While he has not been charged, the FBI is conducting an investigation into the leaks, and he has told The Guardian that he expects the United States will try to prosecute him.
Snowden told the Morning Post that he felt U.S. officials were pressuring his family and also accused them of "trying to bully" Hong Kong into extraditing him to prevent the release of more damaging information.
He vowed to resist extradition efforts if it comes to that, saying he "would rather stay and fight the United States government in the courts, because I have faith in Hong Kong's rule of law."
"My intention is to ask the courts and people of Hong Kong to decide my fate," the South China Morning Post quoted Snowden as saying. "I have been given no reason to doubt your system.''
But Hong Kong lawmaker Regina Ip, a former secretary of security for the territory, said Tuesday that while any extradition process could take months, Snowden isn't necessarily beyond the reach of the United States.
"If he thought there was a legal vacuum in Hong Kong which renders him safe from U.S. jurisdiction, that is unlikely to be the case," she said.
The newspaper said Snowden has been hiding in undisclosed locations inside the semi-autonomous Chinese territory since checking out of his hotel room Monday -- a day after he revealed his identity in an interview with The Guardian.
Snowden told the Morning Post he is not trying to evade U.S. authorities.
"People who think I made a mistake in picking Hong Kong as a location misunderstand my intentions," the newspaper quoted him as saying. "I am not here to hide from justice; I am here to reveal criminality."
The NSA and the National Intelligence director did not immediately respond to a CNN request for comment.
Asked during a media briefing on Wednesday for comment on Snowden's latest claims, U.S. State Department spokeswoman Jennifer Psaki declined. She said she had not seen the latest Morning Post report.
On the defensive
The revelations have renewed debate over surveillance in the United States and overseas in the name of fighting terrorism, with supporters saying the programs revealed by Snowden are legal and have helped stop terror plots. Civil liberties advocates, however, call the measures dangerous and unacceptable intrusions.
Such criticisms have put Obama and his allies on the issue -- both Democrats and Republicans -- on the defensive against mounting criticisms from a similarly bipartisan group of critics demanding changes to rein in the programs.
There also is a sharp division among Americans over the issue.
A Gallup poll released Wednesday found that 44% of Americans believe Snowden did the right thing by releasing details about the classified surveillance programs, while 42% said it was wrong and 14% said they were unsure.
The poll for that question had a 6% margin of error.
It also found that more Americans disapprove than approve of the government's surveillance programs, 53% to 37%. Ten percent had no opinion.
The poll for that question had a 4% margin of error.
Those differences were on display Wednesday when Alexander, the director of the National Security Agency, testified at a hearing into cybersecurity technology and civil liberties.
Officials have been unable to explain controversial data mining programs because they have been classified, Alexander testified.
But Alexander rejected the Snowden's claim that the NSA could tap into any American's phone or computer.
"I know of no way to do that," Alexander said.
But he testified that phone records obtained by the government helped prevent "dozens" of terrorist events.
He would not discuss disrupted plots broadly, saying they were classified. But he did say federal data mining appeared to play a role in helping to disrupt a plot in recent years to attack the New York subway system.
Alexander said information developed overseas was passed along to the FBI, which he said was able to identify eventual suspect Najibullah Zazi in Colorado and ultimately uncover a plot. Zazi pleaded guilty to terror-related charges in 2010.
While not on the roster for Wednesday's hearing, another administration official in the spotlight is Director of National Intelligence James Clapper, whom Democratic Sen. Ron Wyden has singled out for how he answered questions about the telephone surveillance program in March.
In March, Wyden asked Clapper whether the NSA collects "any type of data at all on millions or hundreds of millions of Americans?"
"No sir," Clapper said.
On Saturday, Clapper told NBC News that he answered in the "most truthful or least most untruthful manner" possible.
Clapper told NBC that he had interpreted "collection" to mean actually examining the materials gathered by the NSA.
He previously told the National Journal he had meant that "the NSA does not voyeuristically pore through U.S. citizens' e-mails," but he did not mention e-mails at the hearing.
Fallout over revelations about the NSA's intelligence-gathering has reached the European Union's governing body, where Vice President Viviane Reding raised concerns that the United States may have targeted some of its citizens.
Reding said she plans to raise the issue during a meeting Friday with U.S. Attorney General Eric Holder.
"The respect for fundamental rights and the rule of law are the foundations of the EU-U.S. relationship. This common understanding has been, and must remain, the basis of cooperation between us in the area of Justice," Reding, the EU commissioner for justice, said Wednesday.
"Trust that the rule of law will be respected is also essential to the stability and growth of the digital economy, including transatlantic business. This is of paramount importance for individuals and companies alike."
CNN's Jethro Mullen reported and wrote from Hong Kong, and Chelsea J. Carter reported and wrote from Atlanta. CNN's Paul Steinhauser, Tom Cohen, Michael Pearson, Doug Gross, Shirley Henry, Brian Walker and Pamela Boykoff contributed to this report.