Gardaí have issued a warning to businesses about a growing scam that has seen one company hand over €300,000 to fraudsters.
The fraud involves criminals pretending to be a company's legitimate supplier, and asking to be paid into a new bank account.
The criminals usually send an email that looks like it is from a supplier, telling the company that they have changed their bank details.
That means the money goes to the fraudsters' account when an invoice is paid.
Three men were arrested this week in Dublin after two such alleged frauds were detected.
Detective Chief Superintendent Pat Lordan, who is head of the Garda National Economic Crime Bureau, said: "We're seeing a movement away from other types of fraud to this area of fraud because it's big money.
"You can sit at home in front of your computer, cloak an email and I'll answer that by changing my bank account details and the next payment that comes due goes into the criminal's account.
"So he doesn't have to go near your building, go near your home, go near your business, it's all done online."
DCS Lordan says such emails should not be taken at face value.
He said: "Some of these are occurring for €4,000 and €5,000, some are occurring up into the hundreds of thousands and into the millions.
"Our advice is do not change the banking details of any of your suppliers on your system without talking to somebody that you know within the company. Don't base it on an email that looks like it's your supplier."
- Digital Desk