The US National Security Agency paid millions of dollars to Silicon Valley technology companies to cover the cost of their involvement with the Prism mass surveillance programme.

Leaked documents reveal the NSA covered \'millions of dollars\' of costs for tech companies involved with Prism. (Reuters)

Documents leaked by NSA whistleblower Edward Snowden claim the payouts were made after the secretive Foreign Intelligence Surveillance (Fisa) court ruled that some of the agency's activities were unconstitutional.

Leaked to the Guardian, the documents reveal that technology companies including Google, Yahoo, Microsoft and Facebook incurred the costs to meet new certification demands following the court's October 2011 ruling.

Although the ruling, which have been declassified by the Obama administration, did not concern the Prism programme directly, Snowden's documents describe the problem it created for the NSA and the efforts required to bring its actions into compliance. These efforts involved costs to the technology companies, which were covered by the NSA, although it is not clear if the tech companies actually received any reimbursement.

"The material provides the first evidence of a financial relationship between the tech companies and the NSA," Ewen MacAskill of the Guardian explains.

Millions of dollars

The costs were attributed to a change in the way the NSA requires the Fisa court to sign annual "certifications" that provide the legal framework for surveillance operations. After the October 2011 ruling, these certifications were only being renewed on a temporary basis while the agency worked on a solution.

A leaked NSA newsletter dated December 2012 reveals the costs this solution entailed. It reads: "Last year's problems resulted in multiple extensions to the certifications' expiration dates which cost millions of dollars for Prism providers to implement each successive extension - costs covered by Special Source Operations."

Described by Snowden as the "crown jewel" of the NSA, Special Source Operations handles all surveillance programmes - including Prism - that rely on "corporate partnerships" with telecom companies and internet providers to access communications data.

Silicon Valley companies such as Facebook, Google and Yahoo have all previously denied involvement with, and even knowledge of, the Prism programme, but this latest disclosure by Snowden will raise fresh questions over their involvement and compliance in giving the NSA access to their cache of users' data.

A Facebook spokesperson told IBTimes UK the social network "has never received any compensation in connection with responding to a government data request".

The spokesperson added: "We are not and have never been part of any programme to give the US or any other government direct access to servers, and as we have said repeatedly, we had never even heard of the so-called 'Prism' program until it was first reported by news media. We think the continued misreporting on this matter by the Guardian and others is troubling."

A Yahoo spokesperson told the Guardian: "Federal law requires the US government to reimburse providers for costs incurred to respond to compulsory legal process imposed by the government. We have requested reimbursement consistent with this law."

NSA newsletter
A top-secret NSA newsletter refers to Google and Yahoo as \"Prism providers\" (Guardian)

Despite distancing themselves from the Prism spying scandal, which began on 6 June, both Yahoo and Google were explicitly mentioned in another top-secret NSA newsletter (above) leaked by Snowden. It states that all Prism providers were given new certifications days after the Fisa court ruling.

"All Prism providers, except Yahoo and Google, were successfully transitioned to the new certifications. We expect Yahoo and Google to complete transitioning by Friday 6 October," it read.