BBC: Benny Higgins said the bank knew 'exactly' what the attack was, but could not say more because it was part of a criminal investigation.
'He said all affected customers would be refunded by the end of Tuesday.
'About 40,000 accounts saw suspicious transactions over the weekend, of which half had money taken.
'The bank is still blocking current account customers from making online payments using their debit card, a temporary measure it put in place on Sunday.
'But it said customers would still be able to use their cards for cash withdrawals and chip and pin payments, while bill payments and direct debits would continue as normal.'