Permanent TSB has been forced to apologise to around 100 of its customers after it inadvertently emailed sensitive financial details related to their accounts to a third party.

The breach occurred when a member of the bank’s staff mistakenly emailed information relating to the customer accounts to the account of a single unrelated customer.

The information sent in error included account number and the names of the customers who held that account together with some other material which the bank did not identify in a statement released on Friday night.

Some of the accounts belong to customers caught up in the tracker mortgage overcharging controversy.

Relevant customers were contacted earlier this week and the bank has apologised for the error. It has also reported the data protection breach to the Data Protection Commissioner.

“The breach involved limited information relating to less than 100 customers,” the bank said in its statement. “Neither the addresses nor the contact details of the relevant account holders were communicated in the breach.”

However, despite the “limited” informaiton, some of the details include the fact that the customers were involved in the redress scheme.

The bank also said it had been in contact with the customer who received the email. “That customer has co-operated fully with the bank and has confirmed in writing that the email has been deleted from their email account and that they have no copies of it.”

The bank said it had conducted a thorough investigation of how this incident occurred and has taken steps to ensure it does not happen again.

It is the latest controversy to hit the bank. Earlier this summer the Central Bank concluded an investigation into the manner in which the State-owned bank mismanaged the mortgage accounts of close to 1,400 customers.

The bank is facing substantial fines from the Central Bank and compensation payments to customers of more than €35 million following what was described as a “serious failure” in how it managed interest rates on 1,372 mortgage accounts.

The failures were included mortgage overpayments, mortgage arrears, legal proceedings and a loss of properties in 61 cases.