A further batch of secret government files have been found on a train, it was reported tonight.

The Independent on Sunday newspaper said that the papers, which were handed in to it, covered the UK's policies on fighting global terrorist funding, drugs trafficking and money laundering.

The paper said that they were discovered on a train bound for London's Waterloo station on Wednesday.

The documents apparently include briefing notes for a meeting of the international Financial Action Task Force to be held in 11 Downing Street next week.

They contained 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.

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 the same day that another batch of secret papers relating to intelligence assessments of Iraq and al-Qaida were handed to the BBC after being left by a senior official on a train.

Government sources last night played down suggestions the two incidents were linked.

The Independent on Sunday said it had returned the documents and would not be divulging any details contained in them.