
The Nikon CoolPix camera was bought for £17 by a 28-year-old man from Hemel Hempstead in Hertfordshire and contained the names of al Qaeda members, fingerprints and suspects' academic records as well as pictures of rocket launchers and missiles, according to The Sun.
A Foreign Office spokeswoman said: "We can confirm a police investigation is under way."
However she refused to comment on whether the camera was put on sale by an MI6 operative, despite it containing details of MI6’s computer network.
MI6 is the foreign intelligence service for the UK government with a broadly similar remit as the American CIA.
Terrorism author Neil Doyle said: “These are MI6 documents relating to an operation against al-Qaeda insurgents in Iraq. It’s jaw-dropping they got into the public domain.
“Not only do they divulge secrets about operations, operating systems and previously unheard-of MI6 departments, but they could put lives at risk.”