British spies have snooped on people's visits to online porn websites, according to documents leaked by CIA whistleblower Edward Snowden .
The files appear to detail a top secret programme - creepily codenamed Karma Police - which has been storing and analysing the browsing habits of every visible user on the internet for seven years.
They revelations were published by The Intercept, who say they obtained the information from Snowden.
The Karma Police system collected and stored records of visits to Google, Facebook, Yahoo and Reddit - as well as porn website YouPorn. GCHQ have been correlating logs of websites visited with associated cookie information to identify the viewers.
The Snowden files give some idea of how they mine this data on an unprecedented scale, with the aim of detecting suspicious behaviour by anyone in the world.
The system also allowed spooks to track people who had listened to particular online radio stations, which they say were used to spread radical islamic ideas.
A report included in the leak showed how they selected one listener, from Egypt, and revealed they had also looked at porn site Redtube, Facebook, Yahoo, Flickr, Google, and a website about Islam. The report does not say whether the user was suspected of
a crime or had links to terrorism beyond listening to a radio station.
The Karma Police system shares its name with a Radiohead song, the chorus of which goes: This is what you'll get if you mess with us.