A burglary last month at Precise Mortgages’ site in Wolverhampton saw computer equipment stolen from an administrative office.
This has raised the spectre of possible identity theft of Precise’s 14,000 customers.
Charter Court Financial Services, Precise’s parent, wrote to the mortgage customers, as well as around 11,000 people with savings at fellow business Charter Savings Bank.
In a statement, Charter Court said: “Based on our investigations, working with independent experts and the police, we believe that the personal computers were the motivation for the theft rather than any data.
“While we have no evidence to suggest any personal customer data has in fact been disclosed as a result of this incident and it is unlikely that the data will be discovered, there could be an increased risk of misuse of personal data or identity theft for these customers.
“Promptly following the incident, Charter Savings Bank put in place extra security measures and fraud monitoring procedures and took further steps to reduce the possibility of any recurrence of such an incident.”
The firm said that the stolen computers were not used in or linked to its core banking systems and all the computers were password protected.
It added: “However, we want to be prudent and have written to explain the position to those customers who may be affected as a result.
“In line with our regulatory obligations Charter Savings Bank has of course informed the relevant authorities and we continue to work with them.
“Charter Court Financial Services takes security issues very seriously and we apologise to customers for this incident.”