The United States government hacks Chinese mobile phone companies to gather millions of text messages, former NSA cotracor Edward Snowden said in a report published in the South China Morning Post on Saturday.
Snowden has been hiding in Hong Kong since revealing a massive electronic spying program by the US and was charged with espionage on Friday.
The latest claim comes after Snowden told the SCMP that network backbones in China and Hong Kong were targeted hundreds of times by the NSA.
"The NSA does all kinds of things like hack Chinese cell phone companies to steal all of your SMS data," the former CIA technician said in the latest report published on the SCMP's website late Saturday, which quoted the 30-year-old in an interview conducted on June 12.
Snowden "claims he has the evidence to prove it" the paper said, without elaborating or citing supporting documents.
Government data cited by the paper show that the Chinese exchanged almost 900 billion text messages in 2012, up 2.1 per cent from the year before.
The report did not spell out how the alleged hacking took place, but said Chinese cybersecurity experts have long been concerned about "backdoor" attacks using foreign-made components.
The report came shortly after the the ex-intelligence technician claimed Britain's electronic eavesdropping agency had gained secret access to fibre-optic cables carrying global Internet traffic and telephone calls.
The Guardian said that Government Communications Headqaurters had started processing vast amounts of personal information - including Facebook posts, emails, Internet histories and phonecalls -- and is sharing it with its US partner the NSA.
The SCMP said that its Sunday edition would contain further revelations relating to hacking of a premier Chinese university and the hacking of the Hong Kong headquarters of Pacnet, which owns fibre optic submarine cables in the region.
Hong Kong officials remained tight-lipped on Saturday as to whether they will hold Snowden after Washington charged the former CIA contractor with espionage, theft and "conversion of government property".
The SCMP also said that Snowden remained "safe" in Hong Kong and had not been detained by local police.
The city of 7 million people has maintained a degree of autonomy since its handover to Chinese control in 1997 and operates a different legal system.
The former British colony has a long-standing extradition treaty with the US, but Beijing, which has control over the city's defence and foreign affairs, can veto any ruling. Legal experts have said that any attempt to extradite Snowden could last several years.