Published Friday, 25 April 2014
Ulster Bank's latest glitch occurred over part of the Easter period. (© PA)
The bank said that it was aware of an issue between 4.15pm on Monday and 4.15pm on Tuesday.
It is understood that some customers had money deducted twice from their account after making a withdrawal at an ATM.
On Friday morning, a spokesperson for Ulster Bank said that affected customers had been refunded overnight.
Ulster Bank, a subsidiary of the Royal Bank of Scotland Group, has previously had to apologise for glitches - including in December past, when customers were left without the use of their debit or credit cards and online services and smartphone apps were also affected.
That came after a major technical fault in June 2012 which left hundreds of thousands of customers without proper access to their bank accounts for weeks and resulted in a pay-out of £18m.
© UTV News