The financial institution, Britain's largest retail bank group, later said it had it had fixed the problem that left customers of its members -- Halifax, Lloyds, Bank of Scotland and TSB -- unable to use debit cards or automated teller machines (ATMs).
"We apologise that earlier today, between 3pm and 6pm, some customers were unable to complete their debit card transactions," said a tweet from Lloyds Banking Group.
"Although the majority of transactions were unaffected, we are very sorry for the inconvenience that this will have caused.
"At the same time, some customers encountered problems at approximately half of our 7,000 ATMs. This was resolved by 7.30pm, and all of our ATMs are now working."
TSB chief Paul Pester earlier took to Twitter to apologise for the glitch.
"I'm working hard with my team now to try to fix the problems," he said, explaining that two of the seven servers used to process the bank's debit card payments had malfunctioned.
"It'll take a while to sort the backlog," he added. "Sorry. Customers may have problems for an hour or so."
IT problems have recently plagued UK banks. Shortly before Christmas, a technical fault meant around 750,000 Royal Bank of Scotland customers were unable to use their credit and debit cards.