National Security Agency leaker Edward Snowden urged delegates at a Texas technology conference to "fix" mass surveillance and warned that the spying was "setting fire to the future of the internet."
Mr Snowden, speaking via videolink from Russia where has been granted temporary asylum, said that he had no regrets over leaking details of mass electronic eavesdropping by the US spying agency.
"Would I do it again? Absolutely. Regardless of what happens to me, this is something we had a right to," he told the South by Southwest Interactive Festival in Austin appearing on video screens.
"I took an oath to support and defend the constitution, and I saw the constitution was being violated on a massive scale," he said in response to questions from American Civil Liberties Union lawyers.
Mr Snowden said the changes the American government and private companies have made about managing massive amounts of data helped vindicate his leaks of classified material.
The leaks deeply embarrassed the Obama administration, which in January banned US eavesdropping on the leaders of friendly countries and allies and began reining in the sweeping collection of Americans‘ phone data in a series of limited reforms triggered by Snowden‘s revelations.
Major companies also tightened up safeguards, but Mr Snowden said that is still not enough to protect privacy properly.
“The government has gone and changed their talking points. They have changed their verbiage away from public interest to national interest,“ he said, adding that this poses the risk of losing control of representative democracy.
Speaking to a sympathetic and tech-savvy crowd, Mr Snowden added that the US government still has no idea what material he has provided to journalists.
Last year, Mr Snowden, who had been working at a National Security Agency facility as an employee of Booz Allen Hamilton, leaked a raft of secret documents that revealed a vast US government system for monitoring phone and Internet data.
To many in government and at the National Security Agency, Mr Snowden is a traitor who compromised the security of the United States. But for many at the conference he is a hero who protected privacy and civil liberties.
Kansas Congressman Mike Pompeo, a Republican, had called on the annual festival to cancel Mr Snowden's appearance branding him a "traitor" and "common criminal" over his leaks.
"To me, Snowden is a patriot who believed that what he did was in the best interests of his country," said Roeland Stekelenburg, a creative director at the Dutch Internet firm Infostrada.
Snowden fled to Hong Kong and then to Russia, where he currently has asylum. The White House wants him returned to the United States for prosecution.
Additional reporting: Reuters
