In footage shot by The Guardian newspaper, Edward Snowden said he packed his bags for Hong Kong three weeks ago, leaving behind a "very comfortable life'' in Hawaii, a salary of $200,000, a girlfriend, a stable career and a loving family.

"I'm willing to sacrifice all of that because I can't in good conscience allow the US government to destroy privacy, internet freedom and basic liberties for people around the world with this massive surveillance machine they're secretly building." Snowden said.

But he believed that the value of the internet, along with basic privacy, is being rapidly destroyed by ubiquitous surveillance. "I don't see myself as a hero," he said, "because what I'm doing is self-interested: I don't want to live in a world where there's no privacy and therefore no room for intellectual exploration and creativity."

Once he reached the conclusion that the NSA's surveillance net would soon be irrevocable, he said it was just a matter of time before he chose to act. "What they're doing" poses "an existential threat to democracy", he said.