Revenue officers have seized €7,000 in cash after searching a vehicle at Rosslare Europort.
The find was made in Co Wexford last Thursday with the help of Revenue's detector dog Flynn.
A man, who is originally from Latvia but is now living in Ireland, is currently being questioned in connection with the discovery.
The search came after a routine profiling operation on a vehicle that had disembarked a ferry from Cherbourg in France.
The cash is suspected to be the proceeds of, or intended for use in, criminal activity.
And last Friday officers were granted a three month cash detention order by Judge Gerard Furlong at Gorey District Court.
A Revenue spokeswoman said: "Investigations are ongoing.
"These routine operations are part of Revenue's ongoing work targeting smuggling and shadow economy activity. If businesses, or members of the public have any information, they can contact Revenue in confidence on Confidential Phone Number 1800 295 295."
