The fact that today is pay day for many people has added to customers’ frustrations about the issues.

Many took to Twitter to complain about being unable to access their accounts.

One Twitter user Tweeted: “Can’t log in to my account using Pin Sentry. Error code 80101. Can’t find on the internet what this means. Been on the phone to the number stated for half an hour. Still can’t get in.”

Another Tweeted: “Anyone else having major problems logging onto Barclays online this morning? Can’t get any answers from Barclays themselves & their website says everything is fine?”

At 11.40 am @BarclaysUKHelpTweeted: “If you received a pop-up message when making a transfer or payment using your app or online banking this morning – your payment may still go out over the next 4 hours, so please check after this time. If it hasn’t been processed by then, please resend it.

“Some customers may also be unable to log in to online banking right now. If you receive an error message, please try again in 5 minutes or at a later time.”

The Tweet also directed users to Barclays’ service status page – but this page said that Barclays’ app and online banking were working as they should be.

According to DownDetector.co.uk, a website which monitors website outages, Barclays customers started reporting issues at 8.56am this morning, with nearly 600 customers reporting issues by mid-morning.

Barclays has suffered customer service issues of late with customers reporting waits of over an hour to speak to an operator and get simple queries answered.

A Barclays spokesperson says: “A small number of our customers are having problems logging in to their online banking. We apologise for this and are working to fix it as soon as possible.”