Millions of customers with Barclays Bank in Britain were left unable to withdraw money from cash machines after a computer breakdown stopped them from accessing their accounts.
The company is examining whether the clocks going forward was responsible for the IT problem which affected users across the south of England.
For much of yesterday, customers could not get money from the firm’s hole-in-the-wall machines, Link ATMs or use telephone and internet banking.
Around 1,500 Barclays cash points – half of its southern network – were out of order due to the problem, which occurred in the early hours of Sunday morning, said a company spokeswoman.
The firm has around 4,000 cash machines across the UK.
Barclays customers were able to use their cards to buy goods in shops or get “cashback” from outlets.
Asked if the problem was due to the clocks going forward an hour at 1am on Sunday, for the start of British Summer Time, a company spokeswoman replied: “Given the timing of this its obviously something fairly high on the list (of possible causes), but it would be wrong to speculate until the investigation has been completed.”
She added: “There was no impact on security in any way, accessibility for people to their own accounts (was the problem) not security.”
The glitch was solved by around 4pm yesterday but internet banking still remained offline, said the spokeswoman.
She added: “We would like to apologise to anyone who was affected and whose plans were affected.”