Italian police have arrested eight people in connection with the seizure of $6 trillion (4.5 trillion euros) worth of fake US Treasury bonds.
The counterfeit securities, the equivalent of more than a third of the US national debt, were seized from safety deposit boxes in the Swiss city of Zurich in January.
The eight alleged fraudsters have been accused of carrying out international fraud and other financial crimes.
The year-long investigation by authorities in the southern city of Potenza was carried out in co-operation with Swiss and US authorities. The American embassy in Rome has examined the securities which were dated 1934.
They each had a nominal value of $1 billion.