By Melissa Kite, Deputy Political Editor  Last Updated: 11:30PM BST 14/06/2008  The confidential files were left on a train destined for Waterloo station on Wednesday and outline how trade and banking systems can be manipulated to finance illicit weapons of mass destruction in Iran.  The documents, which were handed by the finder to journalists, also spell out methods for funding terrorism and address the potential for fraudulent use of commercial websites and international internet payment systems. They have been returned to the Treasury.  It is the latest security gaffe involving top-level secret papers and the second such breach in a week.  The Government was already investigating the loss of files relating to al-Qa'eda by a senior intelligence officer in the Cabinet Office, who is understood to have been suspended. That official also left the documents on a train and the finder handed them to the BBC.  In earlier security gaffes, HM Revenue & Customs lost computer discs containing personal details of 25 million people, while the details of three million driving-test candidates were also mislaid.  Documents in the latest incident apparently include briefing notes for a meeting of the international Financial Action Task Force at 11 Downing Street next week.  Last night, a Treasury spokesman said that it regretted the latest incident. He said: "We are extremely concerned about what has happened and will be taking steps to ensure it doesn't happen in the future."  Chris Huhne, the Liberal Democrat shadow home secretary, said: "This is extremely damaging to the Government's fight against terrorism as no one knows where the information may have ended up. This is another appalling embarrassment for an accident-prone government."
Another batch of secret government papers, this time detailing policies on terrorism, has been found abandoned on a train.