Top secret British documents containing an intelligence assessment of the al-Qaeda terrorism network and a classified report on the military situation in Iraq were left on a train in London, the government said Wednesday, dpa reported.
A spokesman confirmed that Scotland Yard had launched an investigation into what was described as a "grave security breach."
The papers were in an orange envelope picked up by a passenger on a train leaving London's Waterloo station Tuesday.
The papers had security coding and were marked "for UK, US, Australian and Canadian eyes only," the BBC reported.
"Two documents which are marked as secret' were left on a train and have subsequently been handed to the BBC," a spokesman for the Cabinet Office said.
"There has been a security breach, the Metropolitan Police are carrying out an investigation."