Criminal Assets Bureau officers have frozen 16 bank accounts containing €540,000 in total, following a search operation in Tipperary and Kilkenny.
According to a spokesperson, the move is a "significant development" in an ongoing investigation into an organised crime group operating in Munster and South Leinster.
The gang also has "considerable links" across continental Europe, according to CAB.
Also seized during this morning's operation, which targeted four residential properties and a business premises, were a 201 Volvo XC90 and financial documents.
Europol have been helping with the investigation and fund transfers worth over €4 million were identified as going from other jurisdictions to Irish bank accounts which are linked to members of the crime group.
Along with CAB officers, the search was conducted by members of the Emergency Response Unit as well as personnel from the relevant garda divisions, and the Garda Dog Unit.
