A technical glitch at Nationwide Building Society has left customers unable to use online and mobile banking services for several hours today.
All Net and mobile banking has been down since this morning, while incoming and outgoing Faster Payments are experiencing delays.
In a statement on its Web site, Nationwide says "We are making every effort to restore service as quickly as possible. We apologise for any inconvenience this will cause you."
Meanwhile, customers taking to Twitter to complain about the outage are being told to use ATMs or visit branches if they want to check their balances or carry out transactions but no timescale has been given for possible fix.
The outage comes on the day Nationwide attempted to score a PR coup with a more old-fashioned channel, opening a flagship branch in London's square mile.
Only last summer the mutual boasted that it experienced a surge in new customers off the back of the IT meltdown which hit RBS and NatWest.
Update:
By 17.00 the Nationwide Web site was claiming that all services were back up and running.