RTÉ Raidió na Gaeltachta has reported this morning that confidential information relating to 550 customers of AIB in Co Galway was mislaid at the end of August.
Customers of AIB in Salthill and An Spidéal received letters from the bank this week informing them of the incident.
The information contained in the documents lost includes customer names, account balances, loan information and bank fees. Customer addresses were not included.
RTÉ Raidió na Gaeltachta journalist Cóilín Ó Neachtain reported today that the material was lost by an employee while moving between branches of AIB in the city for a meeting. The material, which is on paper, has not been found since.
AIB has contacted the Data Protection Commissioner about the matter.
Following queries from RTÉ Raidió na Gaeltachta, AIB confirmed that "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.
"AIB takes its Data Protection obligations very seriously and has reported this incident to the Office of the Data Protection Commissioner."
AIB was not prepared to say which branches were involved, but confirmed they were in Co Galway.