A passenger leaving Malta for Istanbul on Tuesday was found carrying €45,185 in undeclared cash.
Customs said in a statement its officials handed over the case to the Economic Crimes Unit of the police.
This year, Customs had 65 cases of undeclared cash, for a total amount of €1,526,016.
Passengers carrying €10,000 or more in cash or in cheques are obliged by law to declare the money to Customs.