Barclays has apologised for giving wrong information to tens of thousands of customers who started compensation claims over payment protection insurance (PPI).
The bank has admitted telling them they did not hold PPI policies when in fact they did.
It said it would be “proactively contacting” them to put things right.
PPI offered cover for anyone who could not keep up loan repayments if they fell ill or lost their jobs.
But it was often sold to people for whom it was unsuitable and in many cases customers were not even aware that PPI had been added to their loans, credit cards or mortgages.
To find out, customers can contact their banks, building societies or card issuers to ask directly if they have ever held PPI.
Solicitors and claims management companies can also ask the question on their behalf and that is where Barclays has identified a problem.
‘Bulk request’ error
Since 2012, Barclays has provided an online PPI checking tool where these firms can submit requests in bulk for up to 50 customers at a time.
The bank said that in “less than 1.1%” of those cases where requests came via claims management companies, customers were wrongly told that they did not have PPI.
Barclays has put it down to an error which meant that those bulk requests were not always checked against some of the records they hold.
It would not say exactly how many customers were affected, but the BBC understands that the figure is likely to be in the tens of thousands since the problem dates back as far as 2012.