GCHQ captured stills from millions of Yahoo webcam chats, documents leaked by US whistleblower Edward Snowden have revealed.
According to the documents dated between 2008 and 2010, as part of a project named ‘Optic Nerve’ British surveillance agency GCHQ collected from 1.8 million Yahoo accounts around the world to conduct experiments in facial recognition and to detect criminals or terror suspects.
According to the Guardian, the program saved one image every five minutes from the users' feeds, with some of the images being sexually explicit.
As one of the documents put it: "Unfortunately, there are issues with undesirable images within the data. It would appear that a surprising number of people use webcam conversations to show intimate parts of their body to the other person. Also, the fact that the Yahoo software allows more than one person to view a webcam stream without necessarily sending a reciprocal stream means that it appears sometimes to be used for broadcasting pornography."
The documents say that the surveillance began because "Yahoo webcam is known to be used by GCHQ targets".
Another told staff they were allowed to display "webcam images associated with similar Yahoo identifiers to your known target".
Yahoo described Optic Nerve as ‘a whole new level of violation’ of privacy for its users. It denied any knowledge of the program.