An Italian tried to smuggle £10,000 out of Northern Ireland in his underwear.
Officers from the UK Border Agency carrying out checks at Belfast International Airport discovered the money on the man as he was about to board a flight to Rome last Friday.
He could not offer a reasonable explanation for the large-denomination sterling and euro banknotes.
The money was detained under the Proceeds of Crime Act and will be returned only if he can provide proof to a court that the money came from a legitimate source. The man did not travel on the flight.
Maggie Eyden, UK Border Agency assistant director for Northern Ireland, said: "UK Border Agency officers are working hard at all our ports to prevent drugs, contraband or the potential proceeds of crime from entering or leaving the UK.
"Where we suspect that cash may be linked with criminal activity, we have the power to seize it and it will only be handed back if it is later proved to be legitimate."