Three men arrested in Lucan have been held overnight by Gardaí as part of an international fraud investigation.
It involves criminals posing as a legitimate company who are owed money.
Two of the men are suspected of tricking a Spanish company into transferring large amounts of money to an Irish bank account.
The third man is thought to have been behind a similar fraud involving an Irish firm.
Detectives say what's known as an 'Invoice Re-Direction Fraud' involves fraudsters posing as a legitimate company who are owed money.
Most of the money has been recovered.
Senior Gardaí say the arrest of the men - all in their twenties - is "extremely significant".
