A systems update at Clydesdale Bank left its customers without access to their online services this weekend, the bank has said.
This is the latest in a string of IT failures that have left customers without full access to their cash, after outages last year resulted in Clydesdale debit cards not working.
The bank has said that online services should be back to normal for most people.
A spokesman for the bank told Computerworld UK: "We have had a problem with our internet banking service, which has been fixed, the majority of customers should now be able to log on as normal.
"In some specific cases, customers may still be unable to use the service but this will be resolved as systems update over the next 24 hours.
"We are sorry for any inconvenience to our customers."
There were also reports over the weekend that Clydesdale was having problems with its domain name or had been hacked, as users attempting to access the business as usual website were redirected to one that requested a domain name renewal. This was unconfirmed by the bank
Customers took to Twitter to complain. Colin (@Pretentions) said: "Clydesdale Bank online banking has been down for hours and they have the cheek to phone me when I transfer money to Barclays."
Lostair Ltd (@lostair) said: "Serious problems with Clydesdale Bank DNS resolving to incorrect IP address. Looks pretty serious to me."