AIB and Bank of Ireland, in receipt of billions of euros already from the Irish taxpayer, were systematically overcharging customers during the Celtic tiger years, according to the Sunday Tribune.
The repayments to customers will amount to around EUR 100 million, after an investigation by the Financial Regulator.
Meanwhile, the Tribune reported that Michael Moynihan, the chair of the Oireachtas Economic Regulatory Affairs Committee, has begun a new investigation into fresh investigation into overcharging.
"All the records of overcharging will be looked at and each institution will be examined," said Moynihan, who is a TD for Fianna Fáil in Cork North West.
A spokeswoman for the Financial Regulator told the Tribune that "overcharging is a high priority for the organisation and we are working with firms to ensure that errors are corrected and refunds made."