British insurer Royal Sun Alliance has owned up to losing a storage device that contained personal information on premier customers of Lloyds Bank.
The portable storage device - RSA Insurance did not provide detail on the type of device - went missing from one of the insurer's data centres on July 30. It has since been reported to police as stolen.
First reported by the BBC, the storage contained sensitive personal information on Lloyds Bank premier account holders. It affected some customers who had opened accounts between 2006 and 2012 and claimed on their insurance policies.
"The storage device held a range of data, most of which was publicly available information," RSA Insurance said.
"Unfortunately it also held the names, addresses, bank account and sort code numbers for some of our Home Emergency cover customers."
The insurer said it had no evidence the information has been misused, or that any of the leaked accounts have been compromised. It has contacted the customers affected, offering them identity protection for two years.
RSA Insurance will refund a £20 (A$44.50) two-year policy fee for Cifas identity protection cover for those customers who take it out.
The incident is being investigated by the UK police's organised crime unit, and RSA Insurance has reported it to its industry regulator.