Criminals pretending to be bank account holders have been sending forged documents to bank branches instructing them to transfer funds to other jurisdictions.
Commercial bank customers have been targeted in the past five months, including several charitable organisations and companies that have international business.
A garda investigation has assisted in the recovery of €160,000 taken from the account of a well-known charity in September.
It also prevented attempts to steal up to the region of €1.3m during the month of September alone.
A garda operation on 13 October led to the discovery of high-spec items of equipment used to manufacture counterfeit credit cards, and numerous business cheques and cheque books.
The cheques and cheque books appear to have been stolen from the postal system in Ireland and the UK, gardaí say.
Arrests were also made in the Drogheda and Galway searches.
A 32-year-old was before Drogheda District Court this morning.
Michael Tuzuka of Park Square, Grange Rath, Drogheda, was charged with possession of counterfeiting equipment, handling stolen property and theft and attempted theft.
Two other people arrested were released without charge and a file will be sent to the DPP.
The investigation is ongoing.