Permanent TSB has repaid slightly more than €60,000 to customers it overcharged for its current account products.

In letters sent to bank customers over the past week, Permanent TSB said it had uncovered the overcharging as part of an "audit".

The issue relates to a particular type of current account which was offered before the bank launched its free current account last year.

The average repayment to customers will be €12.84, while the total repayment will amount to €61,602.

A spokesman for Permanent TSB said yesterday that the overcharging arose on accounts where the bank offered customers a reduction on certain charges if they maintained an average minimum balance on their account.

He said the bank had now identified "a small number of customers" who did not properly receive the reductions that should have been applied.

These customers, who number fewer than 5,000, will now be reimbursed.

The spokesman said the problem was created when a bank holiday or public holiday coincided with "the start date of a charging period".

This meant that the number of days used to calculate a customer's average account balance was distorted.

"As is normal in Permanent TSB in such matters, the financial regulator has been advised of the issue," the spokesman said.

He confirmed that the bank has completed a review of all accounts that could have been affected by the error.

The repayments that have been organised for affected customers include interest at 3 per cent per year.

Permanent TSB introduced its free banking product a year ago. In 2005, the product attracted 48,500 new customers to the bank.