A senior civil servant is due to appear in court in connection with the loss of top secret documents left on a train, sources said.
An investigation was launched in June after the loss of highly sensitive Whitehall intelligence files relating to al Qaida and Iraq.
Richard Jackson, 37, of Yateley, Hampshire, was summonsed under the Official Secrets Act to appear at City of Westminster Magistrates Court on October 20, the Metropolitan Police said.
A force spokesman said he would answer the following: "That on the 9th day of June 2008 being a crown servant and by virtue of your position as such you had in your possession two documents which it would be an offence under any foregoing provisions of this Act to disclose.
"Without lawful authority you failed to take such care to prevent the unauthorised disclosure as a person in your position may reasonably be expected to take in contravention of S8(1) of the Official Secrets Act 1989."
Jackson is a Ministry of Defence employee, the MoD confirmed.
It is understood he was on secondment to the Cabinet Office at the time of the documents incident.
The documents were passed to the BBC's security correspondent Frank Gardner by a member of the public who discovered them inside an orange cardboard envelope left on a train from London Waterloo to Surrey.
One of the documents was a seven-page report by the Joint Intelligence Committee on "Al Qaida Vulnerabilities", which was understood to look at the state of the Islamist terror network in Afghanistan and neighbouring Pakistan.
The second document, commissioned from the JIC by the Ministry of Defence, contained an assessment of Iraq's security forces.
