Barclays has issued an apology to customers unable to access its mobile banking app last Friday (28 February) morning, with problems yet to be resolved.
Users of Barclays mobile banking application were unable to access account information from 7.30am, due to an unspecified IT issue.
A bank spokesperson said that it is working to resolve the issues, which are continuing to affect customers.
Barclays also issued an apoligy from its official Twitter feed: "We're aware that there are issues with accessing our Barclays Mobile Banking app; this is being looked into on an urgent basis.
"We apologise for any inconvenience caused and we'll update you as soon as we can when we have further information.
"If you need to do any urgent transactions, our other services, such as online banking, are still available."
A spokesperson for the bank said that other services were not affected, with online banking and ATMs operating as normal.
A number of Barclays customers took to Twitter to complain that they were unable to access mobile banking service on payday.
One Barlclays customer David Christian (@davidchristian) tweeted: "I can't log in to my mobilebarclays app, and I gather others are having issues too. Any idea when it'll be sorted? #payday"
Customers of Barlcays were affected by similar problems when its mobile app service went off-line in November 2013 following a software update.
The failure comes not long after the bank announced cutting 1,700 jobs in its branches as it focuses on delivering services through mobile and online channels instead.