Doug Stanglin

USA TODAY

Britain's surveillance agency GCHQ, aided by the National Security Agency, has intercepted and stored the webcam images from millions of Yahoo chats by users who were not being targeted for any wrongdoing, The Guardianreports, quoting from secret documents.

The British newspaper says GCHQ files dated from 2008 to 2010 show that a program codenamed Optic Nerve collected the still images in bulk and stored them in databases.

The report about Optic Nerve is based on documents provided by NSA whistle-blower Edward Snowden, who has received political asylum in Russia.

Yahoo "reacted furiously" to the reported interceptions when approached by the newspaper, The Guardian said. It said the company denied any prior knowledge of the program and accused the surveillance agencies of "a whole new level of violation of our users' privacy."

The article, written by Guardian reporters Spencer Ackerman and James Ball, says these images were stored regardless of whether the users were being targeted by intelligence services.

The Guardian said the British surveillance agency collected images from more than 1.8 user accounts globally in 2008 alone.

One secret document estimated that 3% to 11% of the Yahoo webcam imagery snared by GCHQ contains "undesirable nudity."

The newspaper said that documents provided by Snowden show that Optic Nerve began as a prototype in 2008 and was still active in 2012.

Bulk surveillance on Yahoo users was begun, the documents said, because "Yahoo webcam is known to be used by GCHQ targets," according to the report.

In a statement to the newspaper, a spokesman for Yahoo said:

"We were not aware of, nor would we condone, this reported activity. This report, if true, represents a whole new level of violation of our users' privacy that is completely unacceptable, and we strongly call on the world's governments to reform surveillance law consistent with the principles we outlined in December."

The Guardian said the NSA declined to respond to specific queries about its access to the Optic Nerve system, but did say that the the agency did not ask foreign partners such as GCHQ to collect intelligence that the agency could not legally collect itself.

Alex Abdo, an attorney for the American Civil Liberties Union, called the report "a truly shocking revelation that underscores the importance of the debate on privacy now taking place and the reforms being considered."

"In a world in which there is no technological barrier to pervasive surveillance, the scope of the government's surveillance activities must be decided by the public, not secretive spy agencies interpreting secret legal authorities," Abdo said in a statement.