Jimmy Wales, the founder of Wikipedia, has called on Barack Obama to rein in the National Security Agency as he described the whistleblower Edward Snowden as "a hero" whom history will judge "very favourably".

In an interview with Al Jazeera’s Head to Head show, Wales called for a "major re-evaluation" of the NSA, adding that the public "would have never approved this sweeping surveillance program" had it been put to a vote.

The revelations, Wales said, had been "incredibly damaging and embarrassing to the US".

"It makes it very difficult for someone like me to go out, as I do speak to people in authoritarian countries, and say: 'You shouldn’t be spying on activists, you shouldn’t be censoring the internet', when we [in the US] are complicit in these acts of extraordinary intrusion into people’s personal lives."

Snowden has been granted temporary asylum in Russia having flown there on 23 June this year. He is wanted in the US on espionage charges after passing a trove of documents to journalists from the Guardian and the Washington Post revealing the extent of the NSA's surveillance programs.

"It’s difficult to have a judgment in such a short period of time on a person I don’t know, and where we don’t know what might appear in the future. But, given everything that I know today, he is a hero," Wales told Head to Head host Mehdi Hasan and a live audience at the Oxford University Union.

"He is a person that has been very careful in the materials that he has leaked … they have been in the abstract, he has never leaked anything that would put any particular agents at risk, and so forth. He has exposed what I believe to be criminal wrongdoing, lying to Congress and certainly a shock and an affront, in America, an affront to the fourth amendment. I think that history will judge him very favourably.”

Wales co-founded Wikipedia in 2001 and grew it to become the sixth most popular website in the world. Despite Snowden’s disclosures, the site would not relocate its servers outside the US, Wales said.

“The US remains a jurisdiction for things like freedom of speech, safeguards for internet companies. We would consider it, for sure, but so far we haven’t seen anything that would make us want to leave the US.

“There is a growing sense of concern in Congress about this, a growing sense in Congress that public is angry about this, that they have been misled and I think we are going to see legislation to change this – at least if I have anything to do with this, I think we will.”

In June Snowden was charged with theft of government property, unauthorized communication of national defense information and “willful communication of classified communications intelligence information to an unauthorized person”. The Kremlin has said it will not hand him over to the US government.