News that Prime Minister Stephen Harper's government allowed the largest American spy agency to conduct widespread surveillance in Canada during the 2010 G8 and G20 summits isn't drawing a response from the defence minister or the head of Canada's surveillance agency.

John Forster, chief of the Communications Security Establishment of Canada (CSEC), and Defence Minister Rob Nicholson both pointed to international security and said they couldn't answer questions about top secret documents retrieved by U.S. whistleblower Edward Snowden.

The documents show the federal government allowed the National Security Agency (NSA), the U.S.'s largest spy agency, to conduct widespread surveillance in Canada during the 2010 summits.

The documents are being reported exclusively by CBC News.

"I can't comment in detail on the intelligence operations or capabilities of ourselves or our allies. What I can tell you is that CSEC, under its legislation, cannot target Canadians anywhere in the world or anyone in Canada, including visitors to Canada," Forster said Thursday morning outside the House defence committee.

"We would only do so if we were assisting a law enforcement agency in Canada under a warrant, etc. To do otherwise would be against the law. Further, we cannot ask our allies to do any kind of operations that we ourselves are not permitted to do under law," he said, adding that the commissioner who reviews CSEC has found the agency acts "within the law."

'Did they respect the law?'

Forster wouldn't answer repeated questions about whether Canada would let its allies perform those activities inside Canadian borders.

CSEC Chief John Forster

John Forster, chief of the Communications Security Establishment Canada, says he won't comment on a CBC News report that Canada aided U.S. spying during the 2010 G20 summit in Toronto. (CBC)

"I do partnerships with the Five Eyes allies but I do not ask them to perform actions that is against the law for me to perform in Canada."

The Five Eyes is the name given to the intelligence-sharing partnership between U.S., U.K., Australia, New Zealand and Canada.

In question period, NDP Leader Tom Mulcair asked whether CSEC or anyone else in the government authorize the NSA to spy.

Defence Minister Rob Nicholson also refused to say whether Canada let the NSA spy during the 2010 G8 and G20.

"We cannot comment on specific foreign intelligence activities or capabilities under the law," Nicholson said.

"This organization is prohibited from targeting Canadians. And CSEC cannot ask our international partners to act in a way that circumvents Canadian laws."

Mulcair said Nicholson was telling him something he knows.

"The question was, did they do it? That’s the question," he said.

"Did CSEC obtain the authorization of a judge before authorizing, and helping the Americans to spy on us in Canada during the G20 summit?"

Nicholson repeated his previous response and told Mulcair that should satisfy him.

"We know it’s prohibited, we know they're not allowed to ask, we know they need the authorization of the judge, and the question is: did they respect the law, yes or no? And they failed to answer like usual," Mulcair said.