The Barclays banking app is down leaving customers unable to withdraw money or make payments.
According to Down Detector, more than 600 people have reported online outages for both payments and refunds.
Card, contactless and bank transfers are impacted by the outages, which were first reported at around 8.30am on Saturday.
One user of Down Detector wrote: 'Surprise, surprise, Barclays online banking is down again.....this is not the first time, nor will it be the last.
'I do not understand how a bank of such size and calibre is allowed to have such a useless online banking system.'
