The UK's electronic eavesdropping and security agency, GCHQ, has been secretly gathering intelligence from the world's biggest internet companies through a covertly run operation set up by America's top spy agency, documents obtained by the Guardian reveal.
The documents show that GCHQ, based in Cheltenham, has had access to the system since at least June 2010, and generated 197 intelligence reports from it last year.
The US-run programme, called Prism, would appear to allow GCHQ to circumvent the formal legal process required to seek personal material such as emails, photos and videos from an internet company based outside the UK.
The use of Prism raises ethical and legal issues about such direct access to potentially millions of internet users, as well as questions about which British ministers knew of the programme.
In a statement to the Guardian, GCHQ, insisted it "takes its obligations under the law very seriously". The details of GCHQ's use of Prism are set out in documents prepared for senior analysts working at America's National Security Agency, the biggest eavesdropping organisation in the world.
Dated April this year, the papers describe the remarkable scope of a previously undisclosed "snooping" operation which gave the NSA and the FBI easy access to the systems of nine of the world's biggest internet companies. The group includes Google, Facebook, Microsoft, Apple, Yahoo and Skype.
The documents, which appear in the form of a 41-page PowerPoint presentation, suggest the firms co-operated with the Prism programme. Technology companies denied knowledge of Prism, with Google insisting it "does not have a back door for the government to access private user data". But the companies acknowledged that they complied with legal orders.