In yet another technical blunder for the bank, NatWest has admitted that it pulled its Get Cash mobile app last week due to fraud-related concerns.

"We are aware of an increase in fraudsters targeting customers with phishing attacks to gain access to the Get Cash service. We have currently disabled the Get Cash service while we increase the level of security required," the bank said.

"We will enable the service again once this change is complete. We will refund any customers who have suffered loss as a result of fraud via the Get Cash service," it added.

The app, which allows users to withdraw between £10 and £100 from participating bank ATMs by entering their PIN into their phones, was suspended on 6 October. At the time, NatWest said the suspension was the result of a "planned update" designed to reduce customers' daily withdrawal limits and refused to comment on the app's culpability in fraud schemes.

However, customers complained they were being defrauded out of sums in the hundreds through the Get Cash scheme, according to the BBC's Radio 4 broadcast the Money Box. The programme detailed one NatWest customer's experience of being defrauded out of £950 over 11 contactless ATM withdrawals, despite being unaware of the Get Cash app.

The most alarming aspect of their testimonies was an inference that NatWest was aware of the problem but had failed to disclose the increased risk of fraud to its clients.

Following the technical failings that have plagued the bank since 19 June, NatWest can ill afford another blow to its reputation. The bank's current denial tactics can be assigned to its fear of degrading public trust, but this does not excuse NatWest's failure to inform its customers that they may be at risk.