The office of Prime Minister Stephen Harper is declining to comment on allegations that Canadian authorities allowed a U.S. intelligence agency to spy on dozens of delegates during the 2010 G8 and G20 summits held in Canada.

The allegations are once again shining a light on Canada’s involvement in spying on world leaders, as previously leaked documents revealed that Canadian authorities have participated in similar espionage in the past.

The new allegations are contained in top secret documents retrieved by American whistleblower Edward Snowden that were obtained by the CBC, and outlined in a report Wednesday.

The documents, according to the CBC, show that American authorities used the U.S. Embassy in Ottawa as a command post for the National Security Agency to conduct a spy operation that was approved by Canadian authorities during the summits held in Toronto and Huntsville, Ont. NSA briefing notes, according to the report, described the plan as “closely co-ordinated with the Canadian partner.” It’s alleged that the “partner” is the Communication Security Establishment of Canada.

A spokesperson for the prime minister declined to comment on the report.

“We don’t comment on national security matters,” Jason MacDonald said, Harper’s director of communications. MacDonald did add that “all of CSEC’s activities are subject to review by an independent commissioner who, for 16 years, has reported that the organization has acted lawfully in the conduct of its activities.”

The NSA’s public affairs office told CTV: “While we are not going to comment publicly on every specific alleged intelligence activity, as a matter of policy the U.S. Government has made clear that the United States gathers foreign intelligence of the type gathered by all nations."

According to CBC’s report, the documents say that the NSA and CSEC were intercepting phone calls and hacking into computer systems around the world. The report said that the documents do not reveal the exact targets of the espionage.

Perhaps most noteworthy is that the report suggests the spying went beyond concerns about terrorism and security, and describes part of the NSA’s mandate at the meeting as “providing support to policymaker.”

In question period on Thursday, Rob Nicholson, minister of national defence in the Conservative government, fielded tough questions by opposition MPs.

Responding to NDP Leader Tom Mulcair’s question about whether CSEC got a judge’s authorization before helping the NSA spy, Nicholson said that he couldn’t “comment on specific foreign intelligence activities or capabilities,” adding that CSEC cannot ask international partners to act in any way that circumvents Canadian laws.

Mulcair then retorted: “We know it’s prohibited. We know they’re not allowed to ask. We know they need the authorization of a judge. The question is did they respect the law, yes or no, and they failed to answer like usual. A criminal cover up in the PMO, using a foreign agency to illegally spy on Canadian soil, what is it about obeying the law that this so-called law and order Conservative government doesn’t seem to understand?”

This is not the first time the Canadian government has been implicated in eavesdropping.

Previously released documents by Snowden, a former NSA contractor, revealed that CSEC had spied on Brazil’s ministry of mines and energy.

When the allegations first surfaced, a spokesperson for CSEC said the agency “does not comment on foreign intelligence gathering activities.”

Other documents leaked by Snowden and reported in the media suggest Canada also helped the United States and Britain spy on participants at the 2009 G20 summit in London, England.

British newspaper The Guardian reported earlier this year that alleged espionage in London included efforts to penetrate delegates' BlackBerry smartphones to monitor their email messages and calls. A PowerPoint presentation describing the operation, which was obtained by The Guardian and published in the paper, included a slide featuring the emblem of CSEC.

CSEC, along with the NSA and their British, Australian and New Zealand counterparts, are known as the Five Eyes. The spy agencies have conducted espionage operations together since the end of the Second World War.

With files from Andrea Janus