Seven Internet service providers (ISPs) have filed a legal complaint against the UK's intelligence agency GCHQ.
Since a series of high-profile allegations made last year by US whistleblower Edward Snowden, government agencies have had to face claims of spying and intrusion but this is the first time GCHQ has faced legal action.
ISPs from the UK, US, Netherlands and South Korea are behind the complaint, alongside campaigners Privacy International.
A series of articles in Der Spiegel and the Intercept outline the claims which suggest that the GCHQ conducted illegal network attacks that undermined the "goodwill the organisations rely on."
Other allegations include that the GCHQ infected a Belgian telecommunications firm with malware in order to gain network access and that the agency used an automated system, called Turbine, to scale up network implants.
In a statement, Privacy International explained the reasoning behind the complaint. "The type of surveillance being carried out allows them [the ISPs] to challenge the practices... because they and their users are at threat of being targeted."
The group, which fights to defend privacy across the globe, has also previously filed cases against mass surveillance programmes Tempora, Prism and Upstream.
The ISPs involved in the action are UK-based GreenNet, Riseup (US), May First/People Link (US), Greenhost (Netherlands), Jinbonet (South Korea), Mango (Zimbabwe), and the Chaos Computer Club (Germany).
Cedric Knight, from ISP 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. We say this is unlawful and utterly unacceptable in a democracy."
GCHQ has defending its practices, stressing that all its activities are carried out "in accordance with a strict legal and policy framework which ensures that our activities are authorised, necessary and proportionate."