Culture Secretary Andy Burnham apologised "unreservedly" for a security breach after leaving confidential documents on a train.
It is understood the papers, marked "restricted", were contained in a case left behind yesterday morning when the minister arrived on a train from the North at Euston Station in London.
The missing case was recovered by a passenger on the train's next journey and handed in to police in Glasgow.
The Department for Culture, Media and Sport (DCMS) said although the papers were classified as "restricted", they did not contain sensitive information.
A spokeswoman said the department would conduct a review of security procedures following the blunder.
Mr Burnham said: "What happened was unacceptable and I apologise unreservedly."
The security breach comes after Britain's top counter-terrorist officer was photographed carrying a secret document containing details of an operation to dismantle an alleged al-Qa'ida plot into 10 Downing Street.