A Bank of Ireland employee has lost the personal information of almost 1,000 bank customers on a memory stick.
The details of customers' accounts, phone numbers and addresses were wrongfully copied onto a portable flash drive which was subsequently lost by the employee.
Bank of Ireland has informed those affected about the loss and has promised to monitor their accounts for unusual activity.
The negative publicity comes at a time when the bank was hoping to take advantage of UK residents transferring their cash to Irish banks, because of the Irish government's better guarantees on their savings amid the financial services meltdown.
Graham Cluley, senior technology consultant at Sophos, said, "Sadly, it seems the message about the need for greater care over the transport of sensitive data just isn't getting through to some businesses - or at least that workers cannot be trusted to follow security guidelines and policies, putting the reputation of their companies directly into the firing line."