According to documents supplied to NBC news by Edward Snowden, the UK government attacked hacktivist groups including Anonymous using DDoS attacks.
The DDoS attack, or distributed denial of service, is the same method of attack used by hacktivists in online attacks. Anonymous used this method to attack Visa, for example.
The British Government Communication Headquarters (GCHQ) created a unit named the Joint Threat Research Intelligence Group (JTRIG), or Rolling Thunder. This group carried out an attack that successfully reduced the number of users in Anonymous chat rooms by 80 per cent.
This is the first time JTRIG has been acknowledged as a real group. It was this unit that identified hackers who had stolen confidential information and sent one person to jail for stealing PayPal data.
Documents from a PowerPoint presentation at the 2012 NSA conference, called SIGDEV, detailed how agents engaged hacktivists by posing as fellow hackers. This resulted in the conviction of British hacker Edward Pearson for the theft of 8 million identities from PayPal accounts.
Anonymous, LulzSec and the Syrian Cyber Army are all named in the documents as groups that have attacked government agencies and corporations.
GCHQ explained to NBC news that the actions were justified. "All of GCHQ's work is carried out in accordance with a strict legal and policy framework, which ensures that our activities are authorised, necessary and proportionate, and that there is rigorous oversight, including from the Secretary of State, the Interception and Intelligence Services Commissioners and the Parliamentary Intelligence and Security Committee," it said.
"All of our operational processes rigorously support this position."