Permanent TSB has confirmed that problems with the bank's debit cards have now been fixed.
Debit card customers of Permanent TSB had been temporarily unable to carry out transactions in shops due to a technical fault.
A spokesman for the lender said the difficulties arose due to a problem with a "third party service provider".
AIB also said reported problems with its debit cards have now been fixed.
In a statement TSYS, which processes card payments for the major banks in Ireland, said a "systems slowdown" at its British data centre had affected a number of European clients.
It said its systems were now back to normal and payments were being processed as usual.