The Data Protection Commissioner has been notified after a security breach involving customers of Ulster Bank.

The bank has confirmed that a staff member “inadvertently” dropped a folder containing customer information outside one of its offices.

The folder was subsequently returned.

Ulster Bank says only a “very small” number of customers are affected.

It says it is taking the necessary steps to help protect their details and its contacting all of those involved.

It has also apologised to them.

Ulster Bank is still dealing with the aftermath of its IT fiasco which left hundreds of thousands of customers without access to their accounts for a period of weeks.