Data about British people “may potentially have been accessed” during the data breach at the US credit rating firm Equifax.
The UK arm of the organisation said files containing information on “fewer than 400,000” UK consumers was accessed in the breach.
Last week, Equifax revealed details of the hack and said data on more than 143 million Americans was taken.
The US Federal Trade Commission is investigating how the data was stolen. Information released when details of the breach were disclosed suggest that hackers got at Equifax’s internal systems between mid-May and the end of July this year when the company discovered it had been penetrated.
Data on social security numbers, birth dates and addresses, was taken during the incident.
Equifax is now facing dozens of legal claims over the incident. In a statement, the UK office of Equifax said an internal investigation had shown that data on UK consumers was accessed.
It said data on Britons was being held in the US due to a “process failure” which meant that a limited amount of information was stored in North America.