The building society says a printing error was to blame for customer account details being printed on the back of other customers’ statements.
In 2007, the FSA fined Nationwide Building Society £980,000 after a security breach following the theft of a laptop from an employee’s home.
The affected Skipton letters included the name, account number, balance and interest earnings of other customers.
Skipton says that the information on the back of the letters would not be sufficient to withdraw funds as they are passbook accounts, which require a signature and cannot be accessed via the internet.
In a statement Skipton says: “A third party printer error occurred last weekend resulting in a small percentage of our customers being mailed receiving some incorrect information on their statements.
“The name and account balance of different customers were printed on the reverse of the letters received by 3,115 customers out of a mailing list of 108,000. This did not include the other customers’ address, date of birth or other identifying details. The risk to affected customers is negligible because of this, and the fact that these are passbook accounts which also require a customer signature for withdrawals and are not accessible via the internet.
“Nevertheless, we are writing to those affected to apologise and to reassure them that the correspondence contained insufficient information to enable any unauthorised transactions on their accounts. We are also offering to change the account numbers of any customers seeking additional peace of mind.”
The news comes after Skipton last month came under fire for its decision to scrap the ceiling and hike its standard variable rate from 3.5 per cent to 4.95 per cent.
Skipton also recently announced that 90 staff are at risk of redundancy in a restructure.
Last week Money Marketing revealed that the FSA had accidentally revealed the email addresses of hundreds of IFAs in a mass mail out by failing to use the BCC function.