HSBC has admitted that hardware failure was the cause of a major computer systems crash on Monday that hit thousands of customers trying to use the bank's cash machines, credit and debit cards, and online services.
Many services went down at midday on the New Year public holiday leaving customers unable to withdraw money from cash machines while others had their Switch and credit cards refused in shops.
HSBC's Internet banking service was also hit and people were unable to access their personal accounts or pay bills online for much of the day.
The bank has admitted that the outage was the worst in its history but an HSBC spokeswoman told ZDNet UK sister site silicon.com services were restored late in the evening and are fully operational again today.
"There was an outage due to a hardware failure and we do apologise to all of our customers," she said.
There are no further details available at the moment on the exact nature of the hardware failure but the HSBC spokeswoman said it was not related to usage volumes or the new chip and PIN cards.