Healthcare firm Roche Diagnostics has exposed the personal and medical details of customers on its website. The firm has admitted the security breach but has not explained how it happened.

Roche customers who had registered their details with the firm received the first edition of an email newsletter on Wednesday which included a link via which they could update their personal details.

Users who clicked on that link were directed to a Roche website which displayed the details of someone else.

"I saw the details of the same person several times, then it changed and I saw another person's details several times," said Tim Trent, a newsletter recipient who is also a marketing and privacy specialist. "In all I saw six other people's details."

Trent informed the people whose details he saw and the firm, having received the email on Wednesday morning. Roche spokeswoman Hazel Clarke said that the link was deactivated later that morning.

"We did have that issue this week, on Wednesday," said Clarke. "When we became aware of it we immediately acted to rectify the problem. It lasted for a number of minutes, maybe 90 minutes at most."

Clarke was unable to say how many people had had their details exposed or had seen the personal details of others. She did not say how the breach had happened or how many people the email was sent to.

"The main issue to do with details was stopped immediately and beyond that we need to ensure doesn't happen again, and that is what we are working on now," she said.

The email was in relation to the Accu-Chek range of diabetes testing products.

Trent said he had made a formal complaint to the Information Commissioner's Office. "Some of the details I could access showed that a person was on a particular kind of drug treatment, which isn't good news," said Trent. "Loads of people follow the exhortation to register with Roche Diagnostics, and probably even gave consent to email marketing. But we didn't give them consent to have their data records on public display."

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