AIB has apologised after losing personal information relating to more than 500 of its customers in the west of Ireland.
The bank confirmed on Tuesday that the information had been “mislaid” in Galway on Thursday August 31.
A spokesman for AIB said: “Some confidential information relating to the banking facilities of a number of customers was mislaid on Thursday August 31 in Galway.
“AIB has contacted all impacted customers to explain the matter and to apologise unreservedly.”
The spokesman insisted that AIB takes its data protection obligations “very seriously” and said the bank has reported this incident to the Office of the Data Protection Commissioner.
It is understood the printed material containing names, loan and deposit balances was lost by a staff member.
In a letter sent to affected customers this week, the bank said one of its employees was travelling between two branches in Galway when the data was “mislaid”.
AIB said that “every possible action” had been taken to retrieve the data, but as yet it has not been found.
The material had been gathered as part of a review of what are described as “branch portfolios”.
The bank told customers that their funds cannot be accessed by anyone who may have come into possession of the lost documentation.