after a large-scale fraud was discovered involving Bermuda credit cards.

The Bank of Butterfield customers have been informed that many Visa and MasterCards have been cancelled without notice due to their numbers no longer being secure.

And many bank customers do not yet know their cards no longer work, as they had to be cancelled so quickly and could have transactions turned down in stores.

MasterCard and Visa have been overwhelmed by transactions attempting to be processed, but using expiry dates that do not match up with the real cards.

A statement from the bank said: "Due to a recent increase in attempted fraud on Bank of Butterfield debit and credit cards as reported by MasterCard and Visa, the bank has been forced to cancel some customers' credit card numbers as a security measure.'' One customer who contacted The Royal Gazette , but asked not to be named, only found out her card had been cancelled when she attempted to use it in a shop.

She said: "I knew I had paid my bill, so when a message came up, I was surprised. A woman told me that there had been problems with fake cards trying to do transactions from South East Asia, and the problem was so wide-spread that they had to just cancel all the cards.'' The bank said that new account numbers and replacement cards were being issued to those customers affected by the scam as quickly as possible.

Cards affected include Island Card (Visa), MasterCard Gold and MasterCard Corporate. A spokeswoman for the bank said: "The bank is attempting to contact all customers whose cards have been cancelled.

"If your card is denied by a merchant or if you require further information, please contact the Bank's Card Services Department at 299 3890 during business hours.

"Customers travelling overseas, specifically to the Asia-Pacific region, may also experience delays in card authorisation as a result of the increased security.'' She added: "Bank of Butterfield would like to assure customers that these measures are necessary to protect the security of our account holders. We appreciate your patience and apologise for any inconvenience.''