Exposed: GCHQ's secret plan to tap the world's phone and internet traffic

Internet companies cooperate on GCHQ plan to tap transatlantic fibre optic cables - online spying more comprehensive than feared

British spy agency GCHQ is tapping global internet traffic and phone calls, processing information from around the world which it is sharing with its opposite number in the US, the National Security Agency (NSA).

That is the latest revelation to emerge from the Guardian newspaper's revelations about US-UK secret services' internet spying operations, which have been found to be vastly more extensive than first thought.

The Guardian has released two documents leaked by former NSA contractor Edward Snowden that reveal the extent of GCHQ's internet-tapping ambitions.

Called "Mastering the Internet" and "Global Telecoms Exploitation", they reveal how GCHQ has built a system to scoop up as much internet and telephone traffic as possible, which it passes on to the NSA.

"One key innovation has been GCHQ's ability to tap into and store huge volumes of data drawn from fibre-optic cables for up to 30 days so that it can be sifted and analysed. That operation, codenamed Tempora, has been running for some 18 months," claims the Guardian.

It continues: "GCHQ and the NSA are consequently able to access and process vast quantities of communications between entirely innocent people, as well as targeted suspects."

The operations were first trialled in 2010 and gave GCHQ more access to confidential online information than any other Western intelligence organisation - providing it with data that it can trade with counterparts in the US, UK, Canada, Australia and New Zealand.

It works by tapping into the fibre-optic cables that run through the UK, connecting Western Europe to the US, which also carry data from Africa, Eastern Europe and Asia.

"The GCHQ mass tapping operation has been built up over five years by attaching intercept probes to transatlantic fibre-optic cables where they land on British shores carrying data to western Europe from telephone exchanges and internet servers in north America," according to the Guardian.

This, it adds, was done secretly, but with the cooperation of the companies involved - dubbed "intercept partners" in the documents - under secret agreements under which they were paid for their help.

It has long been claimed by the so-called "tin foil hat brigade" that the UK's internet backbone connects to GCHQ's main centre in Cheltenham, enabling it to spy on UK internet traffic without requiring either a warrant or any other legal oversight.

The latest revelations will add weight to such claims.

As a result, claims the Guardian, GCHQ and NSA are able not just to scoop up the meta-data surrounding people's communications, but the content too, enabling both organisations to build-up detailed files on people's online habits.

And, according to Snowden, GCHQ spies even more voraciously on internet communications than the NSA, partly due to the lack of any robust legal authority to prevent it.

"It's not just a US problem. The UK has a huge dog in this fight," Snowden told the Guardian. "They [GCHQ] are worse than the US."

However, an unnamed Guardian source, claimed that GCHQ's internet eavesdropping operation is undertaken legally and that, although several terabytes of data is scooped up every day, the vast majority of it is discarded, unread.

"If you had the impression we are reading millions of emails, we are not. There is no intention in this whole programme to use it for looking at UK domestic traffic - British people talking to each other... The criteria are security, terror, organised crime. And economic well-being.

"There's an auditing process to go back through the logs and see if it was justified or not. The vast majority of the data is discarded without being looked at ... we simply don't have the resources."

Nevertheless, claims the Guardian, GCHQ's legal authority to tap internet traffic on an industrial scale is legally dubious, based on the 2000 Regulation of Investigatory Powers Act (Ripa) that local authorities have used to spy on, for example, people putting their rubbish out for collection.

While it requires a warrant to be legal, a clause enables the foreign secretary to sign a "certificate for interception" covering broad categories of material "as long as one end of the monitored communications is abroad".