A leading cosmetic surgery provider has been targeted by a computer hacker who may have accessed details of nearly 500,000 people considering procedures.
The Harley Medical Group said it believed the cyber attack was an attempt to extort money from the company and it had contacted police.
Some 480,000 initial inquiry forms submitted online may have been accessed and they include a potential client's name, address and telephone number, the company confirmed.
The form also lists cosmetic procedures, including breast enlargements, liposuction and tummy tucks, in which potential clients can express an interest.
The Harley Medical Group - which has 21 clinics across the UK - has insisted that confidential clinical and financial information was not accessed.
The firm, based in Thames Ditton, Surrey, said it had contacted police and the Information Commissioner's Office about the incident.
The company's chairman, Peter Boddy, has also written to people whose details may have been accessed to apologise.
A spokesman for the Harley Medical Group said: "We acted immediately when we became aware that an individual had deliberately bypassed our website security, gaining access to contact information from initial inquiries, in an attempt to extort money from the company.
"The police and the Information Commissioner were notified and we contacted everyone whose inquiry may have been accessed to apologise and to reassure them that all clinical and financial records remain totally secure.
"We have taken action to further strengthen the security around website inquiries."
An ICO spokesman said: "We have recently been made aware of a possible data breach involving the Harley Medical Group.
"We will be making inquiries into the circumstances of the alleged breach of the Data Protection Act before deciding what action, if any, needs to be taken."