Isle of Man Bank has issued a warning after customers have been targeted by what they describe as "experienced and plausible" fraudsters.
Managing Director Bill Shimins says both corporate and business customers have been involved in what appears to be a concerted attack.
Mr Shimmins says the calls are not from the bank and are invariably an attempt to obtain security information.
He says the bank would never ask customers to provide secret security information over the phone or email.
Customers are reminded that they should never give out card reader codes to anyone over the phone, reveal their full pin or password to anyone.
They should also not click on a link within an email or text message - or call an unrecognised number
If in doubt you should call your bank on a number known to you - preferably from a line not recently used to receive a suspicious call.