About one million dollars has been stolen in Poland from a convoy transporting the money in the south-west.
The money disappeared as five security guards were taking it from Wroclaw to Poznan in the west.
Police are considering the possibility that some of the guards may be involved.
Polish television described it as the robbery of the century, and said the sum involved was greater than all the money taken in bank robberies in the country this decade.
From the newsroom of the BBC World Service