Top US and UK intelligence agencies monitored activist groups and their supporters and targeted them with a campaign of pressure, according to the latest leaked documents from Edward Snowden.
The classified documents detailing the surveillance and pressure tactics were revealed by Ryan Gallagher and Glenn Greenwald, a journalist who has worked closely with former National Security Agency contract worker Snowden to bring the agencies controversial practices to light.
Covert surveillance of Wikileaks began in 2008, shortly after the whistleblower publication first established itself.
As well as targeting Wikileaks founder Julian Assange, the NSA and the UK spy agency Government Communications Headquarters (GCHQ) also carried out surveillance on "the human network that supports Wikileaks".
Those visiting the site were monitored by the intelligence agencies, with both their IP address and Internet search history that led them to the site recorded.
Speaking to Greenwald and Gallagher, Assange labelled the behaviour of the agencies as "reckless and unlawful".
"News that the NSA planned these operations at the level of its Office of the General Counsel is especially troubling," Assange said.
"Today, we call on the White House to appoint a special prosecutor to investigate the extent of the NSA's criminal activity against the media, including WikiLeaks, its staff, its associates and its supporters."
Other groups including the file-sharing site Pirate Bay and hacktivist organisation Anonymous were also reportedly targeted by the agencies.