A database containing mobile phone numbers and information about their use has been stolen from a company carrying out forensic investigations for police forces across the UK.
Forensic Telecommunications Services recovers and extracts data from mobile phones, PDAs and other communications equipment so it can be used by police in serious criminal investigations - including murder and kidnap cases - and in anti-terrorism work.
The company admitted that administrative data and case files -- including some from cases currently before the courts -- were held on the server stolen from its premises in Kent during a break-in. Other computer equipment was also stolen.
The incident was reported to Kent police on 7 August.
FTS said the server was security protected, adding: "None of the data stored on the server in any way compromises ongoing police operations."
Data held on the stolen machine was made up of cases that have already passed through the judicial process and current cases. FTS has restored the data through its business continuity process and is now undertaking a full security review.
But Kent police are appealing to members of the public who may have information about the theft to call the Crimestoppers phoneline.
A Scotland Yard spokesperson confirmed the stolen machine contained data relating to Metropolitan Police investigations and that officers involved in these cases had been made aware of the theft.
"We do not believe from the research we have conducted to date that the stolen data will have any serious impact on current or historic investigations," he added.
FTS is one of "a number" of firms used by the Met to analyse telephone data.
The company also has a national contract with HM Revenue and Customs.