AIB has begun an investigation into whether there was any fraud in transactions concerning certain funds in the deposit book acquired from Anglo Irish Bank.

The bank said the investigation was triggered by a customer inquiry and concerned certain discrete funds.

If fraud is uncovered, AIB said customers would suffer no financial loss.

"In the event that fraudulent activity has occurred, AIB confirms any such transactions will be for the account of the bank," it said.

The Garda Bureau of Fraud Investigation and the Central Bank have been informed of the matter.

Some €7.1 billion in deposits held in Anglo Irish Bank were transferred to AIB as part of the restructuring of the institution, a condition of Ireland’s finance agreement with the EU and the IMF.