The City watchdog has launched an official investigation into the massive hack of Equifax which exposed millions of people's personal data.
"The [Financial Conduct Authority] FCA announces today that it is investigating the circumstances surrounding a cybersecurity incident that led to the loss of UK customer data held by Equifax Ltd on the servers of its US parent," it said in a statement.
It said it was making knowledge of the investigation public "given the public interest".
The credit agency revealed the details of 145.5m people were exposed, largely affecting customers in the US. But it admitted that the data of some UK customers was exposed as a result of some information being stored on a US server.
It admitted that 15.2m records of 700,000 people were affected in the UK.
Equifax said it is already working closely with the regulator and other authorities and welcomed the probe. In a statement it said:
"We welcome this opportunity to learn the lessons from this criminal cyber attack in order for all businesses to better protect consumers in the future. Cybercrime is a real and ever-present risk faced by all companies, so it is important that government, regulators and businesses work together to combat this growing threat. We see today’s announcement as a continuation of that process.”
MPs are also probing the firm. The chair of the Treasury select committee Nicky Morgan said it was right for the matter to be investigated and added that the group would ask the FCA questions about it when it takes evidence from it next week.