The National Security Agency (NSA) spied on governments participating in the Copenhagen climate talks in 2009, new documents leaked by whistleblower Edward Snowden show.

The NSA monitored communication between countries before the conference and had planned to tap private discussions between leaders and teams of negotiating countries throughout the period of the meetings from 7 December to 18, according to documents published by the Huffington Post and Danish daily Information.

According to the documents, "leaders and negotiating teams from around the world will undoubtedly be engaging in intense last-minute policy formulating; at the same time, they will be holding sidebar discussions with their counterparts, details of which are of great interest to our policymakers".

Phone calls and emails intercepted

The agency gathered information during the summit by intercepting phone calls and emails, though the documents provided no other details, according to the Huffington Post.

Members of the Danish negotiation team are reported to have divulged that the US and Chinese delegations were "peculiarly well-informed" about closed-door discussions.

"They simply sat back, just as we had feared they would if they knew about our document," one source told Information.

"They made no constructive statements. Obviously, if they had known about our plans since the fall of 2009, it was in their interest to simply wait for our draft proposal to be brought to the table at the summit...I was often completely taken aback by what they knew."

The documents published on an internal NSA site on the first day of the Denmark conference, 7 December 2009, also stated: "Analysts here at NSA, as well as our Second Party partners, will continue to provide policymakers with unique, timely, and valuable insights into key countries' preparations and goals for the conference, as well as the deliberations within countries on climate change policies and negotiation strategies."

The "Second Party partners" here may refer to the "Five-Eyes" group of nations sharing intelligence comprising US, UK, Canada, Australia, and New Zealand.

The US has defended the NSA intelligence activities as important to fighting terrorism around the world, but the latest Snowden documents again indicate that the agency is involved in promoting broader US interests in the international arena, according to analysts.

The allegations that the NSA monitored private communications of governments during the summit might deter governments from expressing their ideas and policies more openly in future negotiations.

Alden Meyer, director of strategy and policy for the Union of Concerned Scientists, said he worried that the disclosure might cause the parties to "start becoming more cautious, more secretive, and less forthcoming" in the negotiations.

"That's not a good dynamic in a process where you're trying to encourage collaboration, compromise, and working together, as opposed to trying to get a comparative advantage," he added.