Rogue employees at a major mobile phone company illegally sold millions of customer records to rival firms, Britain's information watchdog said Tuesday.
Christopher Graham, the information commissioner, said the case was a serious breach of data privacy, and he called for harsher punishments for offenders.
"The existing paltry fines ... are simply not enough to deter people from engaging in this lucrative criminal activity. The threat of jail, not fines, will prove a stronger deterrent," he said.
The mobile phone company _ which Graham said could not be identified because an investigation was ongoing _ alerted Graham's office after it found out about the suspected trade. Personal data, including customers' contract expiry dates, were sold to several rivals, which then used the material to cold-call customers to offer them an alternative deal, the office said.
"The number of records involved runs into the millions, and it appears that substantial amounts of money changed hands," the government body said in a document submitted to the Ministry of Justice.
Graham said his office was considering the evidence and preparing to prosecute those responsible.
The Data Protection Act prohibits the selling on of data without prior permission from the customer. Offenders could be fined thousands of pounds (dollars).