Thousands of T-Mobile customers' private details were sold on to rival firms in a major data selling scandal, it was revealed yesterday.
A spokesman for the company confirmed it alerted the data protection watchdog after it discovered contract information was being passed on “without our knowledge”.
The Information Commissioner, who is investigating the breach of data protection rules, said thousands of mobile phone owners had their details sold on for “substantial sums”.
A spokesman for the company said the situation was “deeply regrettable” and suggested it was an industry-wide problem. The company had been asked to keep the problem a secret to avoid prejudicing a criminal prosecution.
He said: “T-Mobile takes the protection of customer information seriously.
“When it became apparent that contract renewal information was being passed on to third parties without our knowledge, we alerted the Information Commissioner's Office (ICO).
“Working together, we identified the source of the breach, which led to the ICO conducting an extensive investigation which we believe we will lead to a prosecution.
“While it is deeply regrettable that customer information has been misappropriated in this way, we have proactively supported the ICO to help stamp out what is a problem for the whole industry.”
The commissioner, Christopher Graham, said names, addresses, telephone numbers and other contract information were stolen and sold on to competitors. T-Mobile is Britain's fourth biggest mobile company and a subsidiary of German firm Deutsche Telekom. It has an estimated 16.6m customers.