A major data selling scandal has hit thousands of T-Mobile customers who have had their data sold on without the knowledge of the company, it has been revealed.

The data protection watchdog was alerted by the company after it discovered the information was passed on without T-Mobile's knowledge. The Information Commissioner said the details were sold on for "substantial sums".

T-Mobile had been asked to remain quiet over the issue to avoid prejudicing a criminal prosecution. A company spokesman described the incident as "deeply regrettable", but hinted that it was an industry-wide problem.

"T-Mobile takes the protection of customer information seriously," said a T-Mobile spokesman. "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."

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