Former National Security Agency systems analyst Edward Snowden says that he did not take any secret NSA documents to Russia.
And he says that intelligence officials in China as well as Russia could not get access to the documents he had obtained before leaving the US.
In an interview with The New York Times, Mr Snowden said he handed over all the documents he had obtained to journalists during his stay in Hong Kong.
Mr Snowden said he did not retain copies of the documents and did not take them to Russia "because it wouldn't serve the public interest," the newspaper reported.
He said his familiarity with China's intelligence abilities allowed him to protect the documents from Chinese spies while he was in Hong Kong.
"There's a zero percent chance the Russians or Chinese have received any documents," he said.
Mr Snowden's leaks of highly classified material have resulted in numerous news stories about US surveillance activities at home and abroad and sparked debate about their legality, and the privacy implications for average Americans.
The newspaper reported that the interview took place over several days in the last week and involved encrypted online communications.
It said that Mr Snowden asserted he believed he was a whistleblower who was acting in the nation's best interests by revealing information about the NSA's surveillance dragnet and huge collections of communications data.
Mr S nowden said that he had helped US national security by prompting a badly needed public debate about the scope of the intelligence effort.
"The secret continuance of these programmes represents a far greater danger than their disclosure," he said.
Mr Snowden faces espionage charges in the US. On August 1 he was granted asylum in Russia, which is allowing him to remain there for one year.