The United States spied on a G-20 meeting in Toronto with the assistance of Canada's government, according to new documents leaked by former NSA contractor Edward Snowden.

The Canadian Broadcasting Company revealed the news, noting the surveillance was carried out not only to watch for potential terrorist threats but also to further the policy goals of leaders at the summit.

President Obama and 25 other world leaders were gathered in Canada for six days in 2010. According to the documents, the U.S. converted its Ottawa embassy into a security command post throughout the summit, with its efforts “closely co-ordinated with the Canadian partner.”

The National Security Agency's Canadian “partner” is Communications Security Establishment Canada (CSEC), which, like the NSA, obtains intelligence by hacking computer networks, intercepting phone calls and engaging in other forms of digital espionage.

The documents, the CBC notes, do not specify who was being targeted by the intelligence operation, but the effort came just a few months after a 2009 summit in London, where previous leaks have implicated the U.S. in hacking the phones and emails of diplomats attending the summit.

If Canada provided the U.S. with direct support in such espionage efforts, it would be of questionable legality, as Canadian law requires a warrant for the CSEC to target anybody for surveillance, including foreign visitors, and forbids the agency from allowing a foreign intelligence service to do anything the CSEC is forbidden to do., a Canadian civil liberties group, was quick to condemn the spying effort.

“[The CSEC is] undermining democracy here at home, while deeply damaging Canada’s international reputation as a fair and honest partner,” said the group's executive director, Steve Anderson.

When reached by The Associated Press, the office of Canadian Prime Minister Stephen Harper declined to comment, saying it did not speak on “operational matters related to national security.”

The new leaks are not the first to involve Canada's security establishment. In early October, another series of documents exposed Canadian eavesdropping on Brazil, sparking a row between the two countries.

Canada is part of the UKUSA, or “Five Eyes” Agreement between the United States, United Kingdom, Canada, Australia, and New Zealand. The agreement, dating to the early days of the Cold War and only made public in 2005, strongly links the intelligence communities of the five Anglosphere states in carrying out surveillance and espionage around the world.