Monzo urges 480,000 customers to change pins as banking details exposed to unauthorised staff

Digital bank Monzo has urged almost half a million customers to change their PINs after it emerged banking information was exposed to what is being termed unauthorised staff.

About one in five of the bank’s 2.6 million customers, or around 480,000 UK accounts, were affected by the issue.

In a statement, the company said the problem has since been resolved and apologised to those hit.

"We've fixed an issue that meant we weren't storing some customers' pins correctly,” it said.

The app-only bank told customers to change their pin numbers (Monzo)

"On Friday August 2, we discovered that we'd also been recording some people's pins in a different part of our internal systems (in encrypted log files).

"Engineers at Monzo have access to these log files as part of their job."

The company said it deleted the information stored in this way.

"As soon as we discovered the bug, we immediately made changes to make sure the information wasn't accessible to anyone in Monzo.

"By 5:25am on Saturday morning, we had released updates to the Monzo apps.

"Over the weekend, we then worked to delete the information that we'd stored incorrectly, which we finished on Monday morning," it said.

About one in five of the bank's customers were affected.

"We've checked all the accounts that have been affected by this bug thoroughly, and confirmed the information hasn't been used to commit fraud", the bank added.

The company contacted customers to let them know they should change their pin.

"If we've contacted you to tell you that you've been affected, you should head to a cash machine to change your pin to a new number as a precaution," the statement said.

Customers affected have also been advised to update their Monzo apps.

People who have noticed unusual activity on their Monzo account are advised to contact the company.

"If we haven't emailed you, you haven't been affected," the company said.

"But you should still update your app to the latest version."

Monzo's statement added that it was "really sorry about this".

The bank, which is popular with millennials and known for its coral pink cards, is valued at £2 billion.