Glenn Greenwald — the journalist who, through his source Edward Snowden, revealed a massive domestic and foreign spying operation by the U.S. National Security Agency — says documents outlining Canadian surveillance will be published.

“The documents are quite complex. There are a lot of them. There is enormous amounts of reporting to do in Canada, one of the most active surveillance agencies in the world, because of how closely they work with the NSA,” Greenwald told Brent Bambury, host of CBC Radio’s Day 6.

“There are many, many, many more significant documents about Canadian surveillance and partnership with the NSA that will be reported and, I think, will be quite enlightening for the people of Canada.”

Greenwald, whose work helped spur an international debate on surveillance and privacy, dismisses critics who claim publishing classified government documents puts people in danger.

“I think not publishing the leaks puts [people] in danger because when you have a system of government in which people can exercise great power in the dark, that’s what is dangerous,” he said.

“Terrorists have long ago known that the U.S. and U.K. governments do everything possible to monitor their communications … We didn’t tell the terrorists anything they didn’t already know. What we’ve told people that they didn’t already know, ordinary citizens all around the world, is that this spying system is directed not at the terrorists but at them."

'Everything should be questioned'

Earlier this year, British agents oversaw the destruction the Guardian newspaper’s hard drives after the paper published revelations from Snowden’s leaks — a move Greenwald says demonstrated how desperate the government was to suppress the information.

Edward Snowden worked as a contract employee at the U.S. National Security Agency. (The Guardian/Associated Press)

“I think what it also underscored is just how precarious press freedoms are in the very Western countries that love to lecture the world about how vital and important they are,” he said.

“Everything should be questioned. No institutional authority is ever so formidable that they should be entitled to shield themselves from challenge and questioning. And I think that lies at the heart of the value of privacy, I think it lies at the heart of a belief in free speech as well.”

On Saturday, the Guardian confirmed its editor, Alan Rusbridger, will appear before a U.K. House of Commons committee over its decision to publish Snowden’s intelligence files after warnings from security chiefs that the leaks damaged U.K. security.

Disclosures about the activities of Britain's GCHQ eavesdropping agency and its close co-operation with the NSA have embarrassed British Prime Minister David Cameron and angered lawmakers in his ruling Conservative party who say they have compromised national security.

Civil liberties groups say the files have shown the need for more effective controls over intelligence gathering but spy chiefs have been highly critical about their publication.