More secret files found on a London train
What is going on? Who is taking these on a train and then just casually leaving them behind? It's not like an umbrella you know!
See previous NowPublic coverage here.
The Independent on Sunday says it was handed the documents, which cover fighting global terrorist funding, drugs trafficking and money laundering.
The files, relating to a meeting of financial crime experts, were found on the same day as another batch of secret papers were handed to the BBC.
A Treasury spokesman said the government was "extremely concerned".
The documents apparently include briefing notes for a meeting of the international Financial Action Task Force (FATF) to be held in 11 Downing Street next week.
Yard 'not involved'
A Treasury spokesman said: "We are extremely concerned about what has happened and we will be taking steps to ensure that it doesn't happen in the future."
The papers were found on train bound for London Waterloo on 11 June, the same day that another batch of secret papers relating to intelligence assessments of Iraq and al-Qaeda were handed to the BBC after being left by a senior official on a train.
The confidential files were said to include details of how trade and banking systems could be manipulated to finance illicit weapons of mass destruction in Iran.
They also discussed methods of terrorist funding and the potential fraud of commercial websites and international internet payment systems.
The Independent on Sunday said it had returned the documents and would not be divulging any details contained in them.