Britain's MI6 intelligence service is investigating how a camera holding sensitive information about al-Qaida suspects came to be lost by one of its agents and then sold on eBay, police said on Tuesday.
"We can confirm we seized a camera after a member of the public reported it," said a statement by police in Hertfordshire, north of London, after the camera was handed into a police station.
"Intelligence services are investigating," the statement added.
A 28-year-old Briton bought the Nikon Coolpix camera for 17 pounds ($31) and discovered the secret material when he downloaded pictures after a vacation in the United States, the Sun newspaper reported.
A document stored on the camera's memory card was marked "top secret" and detailed an encrypted computer system used by intelligence officials, it said. The buyer was not identified.
Its memory had names of suspected al-Qaida members and suspects' academic records as well as pictures of rocket launchers and missiles, the Sun said.
The incident is the latest in a series of embarrassing data losses to affect the intelligence services and the government.
On Monday, prosecutors said a senior public official who left top secret intelligence assessments of al-Qaida and the security forces in Iraq on a London commuter train is due to face charges under the Official Secrets Act.
Last year, a civil servant lost computer disks containing the names, addresses and bank details of 25 million people, while in January, the Ministry of Defense said it had lost a laptop containing personal data on 600,000 recruits.
The Home Office said in August that a contractor had lost personal details of every prisoner in England and Wales.