AIB should establish what customers were overcharged for foreign exchange transactions, even if a lot of costly work was involved, the Tánaiste, Ms Harney, said yesterday.

She said that, although it might be cheaper for the bank to simply make a €14 million payment to a charity, she believed it would be better for the bank if it went to the effort of establishing who was out of pocket and reimbursed them. This would help "restore confidence".

She said she also agreed with the suggestion that the bank should not try to establish who was out of pocket by requesting customers to check their files. She said if the bank was not able to identify the customers affected, then that would raise the question as to why not.

Speaking on RTÉ radio, Ms Harney said she was surprised that the overcharging had been discovered as far back as 2002 and nothing done about it for so long.

"If it was undercharging I am certain it would have come to light a lot sooner," she said.

She believed the overcharging was discovered by the bank's strategic development unit in 2002.

She said she would have thought, given its recent history, that the bank's internal controls would be such that "when things like this came to light, they would go right to the top very quickly".

Ms Harney added that she was sure the consumer director of the Irish Financial Services Regulatory Authority (IFSRA), Ms Mary O'Dea, would be in contact with AIB and the other banks in relation to their internal procedures.