British police launched an investigation after two top secret government documents relating to al-Qaeda and Iraq were found on a train in London.
In the latest security breach for Prime Minister Gordon Brown's government two documents, which are marked as secret, were left on a train and have subsequently been handed to the BBC
The spokesman declined to discuss the contents of the documents, but the BBC said they were an intelligence assessment of al-Qaeda and an 'embarrassing' appraisal of Iraq's security forces.
The BBC reported that the documents, in an orange cardboard envelope, were left on the seat of a train which was about to pull out of London's Waterloo station.
The broadcaster said the passenger who found the files, which it said were marked 'UK Top Secret', took them to its security correspondent, who had read them.
The intelligence assessment of al-Qaeda was seven pages long and so sensitive that it was marked 'for UK/US/Canadian and Australian eyes only', the BBC reported.
The other pertained to the state of Iraq's security forces and contained "embarrassing" revelations, it said.
They had been in the possession of a 'very senior intelligence official' working in the Cabinet Office, the BBC said.
It is believed they were both made by the government's Joint Intelligence Committee.
