Gardaí seized €400,000 and raided sites in Wexford, Dublin and Meath as part of an intelligence-led operation into money laundering by a feared organised crime gang.
The seizure followed the questioning by gardaí of an Irish man and a Polish national who were parked in a Rosslare lay-by in Wexford with a cattle truck and a car.
Gardaí attached to the National Drugs and Organised Crime Bureau (NDOCB) became suspicious of the duo parked off the N25 and searched the vehicle.
That led to the discovery of the cash.
Both men - an Irishman (53) and a Polish national (35) - were arrested and taken to Wexford garda station.
They were being questioned about alleged money-lauding operations contrary to the Criminal Justice, Money Laundering and Terrorist Financing Act, 2010.
Both can be detained for up to 24 hours.
Following the discovery of the €400,000, gardaí conducted follow-up searches at addresses in Swords in Dublin and Trim in Co Meath.
The detection was the result of an intelligence-led Garda operation involving lengthy surveillance.
Garda chiefs said the operation was "very significant" in the ongoing work of the Special Crime Task- force.