The GCHQ electronic eavesdropping centre faces an unprecedented joint legal complaint from internet service providers accusing it of unlawfully monitoring private communications.
Seven ISPs from around the world have joined forces to lodge a protest that GCHQ has used illegal tactics and had “targeted, attacked and exploited” networks which are used by millions of people.
It follows accusations by the American whistleblower Edward Snowden that the Cheltenham listening post is covertly monitoring large quantities of data from fibre optic cables carrying telephone calls and internet traffic.
The complaint was today registered with the Investigatory Powers Tribunal, which considers grievances about surveillance operations conducted by public bodies.
It has been lodged by ISPs from Britain, the United States, the Netherlands, Germany, Korea and Zimbabwe in partnership with the campaign organisation Privacy International.
A series of allegations includes a complaint that GCHQ targeted employees of a Belgian company, Belgacom, with malicious software to gain access to its network.
Eric King, Privacy International’s deputy director, said: “These widespread attacks on providers and collectives undermine the trust we all place on the internet and greatly endangers the world’s most powerful tool for democracy and free expression.”
Cedric Knight, of UK-based GreenNet, said: “Snowden’s revelations have exposed GCHQ's view that independent operators like GreenNet are legitimate targets for internet surveillance, so we could be unknowingly used to collect data on our users.”
He added: “Our entire modus operandi is threatened by this illegal and intrusive mass surveillance.”
A GCHQ spokesman said its operations were “carried out in accordance with a strict legal and policy framework which ensures our activities are authorised, necessary and proportionate”.
He said that there was “rigorous oversight” of its activities and stressed that the UK’s interception regime was entirely compatible with the European Convention on Human Rights.