Barclays bank is in the firing line after thousands of confidential customer files were stolen.
The breach, which contained the information of around 2,000 individuals including names, addresses and passport numbers, were sold for use by fraudsters. Barclays has said it will be informing those concerned but not all the names in the file were its customers.
Now the Financial Conduct Authority is looking into the matter and, should it find reason to, will impose unlimited fines on the banking firm. The Information Commissioner's Office, which can charge fines of up to £500,000, is also looking into the matter.
The customers involved in the breach are believed to have been part of a now defunct Barclays Financial Planning business.
Most of the names featured in the list are those of elderly customers, who are now being targeted with investment scams.
Barclays bank has used a blog post to thank the Mail on Sunday, where the leak was originally published, for bringing the issue to its attention.