The British electronic intelligence gathering agency GCHQ is reported to have collected webcam images from millions of internet users.
Britain's The Guardian newspaper says GCHQ, with the help of the American National Security Agency, intercepted and stored still images of Yahoo webcam chats from 2008 to 2010.
Photo: AFP
Yahoo says it is unaware of this activity which if true is completely unacceptable.
According to leaked documents, sexually explicit images were among those gathered - although not intentionally.
In a statement GCHQ said all of its actions are in accordance with the law.
In one six-month period in 2008 the operation called Optic Nerve captured images from 1.8 million users.
The Guardian's report originated from documents leaked by whistleblower Edward Snowden.