It has been confirmed that 120,000 Bank of Ireland customers were double charged for Laser card transactions over the weekend.
The bank said the issues were resolved last night.
It is understood that some Laser card holders who used their cards since last Friday have been double charged for the same purchase, possibly repeatedly over a number of days.
The bank has yet to clarify whether the problem also affected transactions made after Friday.
The payments of direct debits and cheques were not affected, but standing order payments may have been delayed by one day.
A spokeswoman refused to confirm the amount of money involved, but it is believed it could run into millions of euro.
A Bank of Ireland spokeswoman said all refunds had been made including all overdraft fees and penalties charged to customers as a result of the incorrect charges to their card.
Customers who are concerned should contact Bank of Ireland's Banking 365 on 1890 365 365 or contact their local branch.
