The Xbox 360 Kinect camera was at one point evaluated for its potential use in mass surveillance of people in their homes, according to documents disclosed by The Guardian.

This information comes from files dated between 2008 and 2010, as leaked by NSA whistle-blower Edward Snowden. The documents suggest during this period a surveillance program codenamed Optic Nerve collected images of internet users through Yahoo's webcam chat service with the help of the United States National Security Agency.

While the agency has allegedly intercepted and stored millions of images of Internet users not suspected of wrongdoing through webcams on Windows PC and Mac systems, the Xbox 360 peripheral was also evaluated for its potential as surveillance technology.

Presentation documents from the British surveillance agency Government Communications Headquarters (GCHQ) describe Microsoft's Kinect peripheral as generating "fairly normal webcam traffic," adding that it was under evaluation at the time. It remains unclear whether the GCHQ was successful in capturing images using Kinect technology.

However, these files highlight a six-month period during 2008 when the agency collected over 1.8 million images of Yahoo users through webcams. According to these documents, webcams would take photos every five minutes and send images directly to a GCHQ database.

"Face detection has the potential to aid selection of useful images for 'mugshots' or even for face recognition by assessing the angle of the face," reads a selection from the documents via The Guardian. "The best images are ones where the person is facing the camera with their face upright."

Surveillance analysts were said to have been shown faces of those with similar usernames to targetted individuals. Optic Nerve allegedly began as a prototype in 2008 but remained active in 2012.

Microsoft has previously stated in its Privacy guidelines it will not use Kinect to spy on its user base, nor will it cooperate with the government by giving out access to the technology. Prior to the launch of Xbox One, the company told Polygon that Kinect is not capable of recording or transmitting audio or video to Microsoft's servers without the consent of the user.

"Xbox One does not understand or try to capture conversations in your room," Microsoft told us at the time. "When Xbox One 'listens,' it is waiting to hear very specific voice commands; all other conversation is irrelevant.

"For example, the words 'Xbox Turn Off' cause the console to power down, while 'Xbox On' causes it to power up. In order for Kinect to respond you must first say 'Xbox' followed by your request, for example, if you just say 'pause,' Xbox One will not pause until you say 'Xbox Pause.' Xbox does not listen to, track or store conversations of people talking in the room. We'll share more about specific voice commands and tips to control your Xbox One using voice closer to launch."

In a statement to Polygon today, a Microsoft spokesperson said: "Microsoft has never heard of this program. However, we're concerned about any reports of governments surreptitiously collecting private customer data. That's why in December we initiated a broad effort to expand encryption across our services and are advocating for legal reforms."

Angry Birds' Rovio Entertainment were similarly singled out earlier this year following allegations that both the NSA and GCHQ collected user data from a "leaky" angry birds app. Rovio stated it does not "share data, collaborate or collude with any government spy agencies such as NSA or GCHQ anywhere in the world," adding that if surveillance agencies were targeting advertising networks such as the one used in Angry Birds, then "it would appear that no internet-enabled device that visits ad-enabled web sites or uses ad-enabled applications is immune to such surveillance."