A Shropshire technology company was today revealed as the last known location of a missing computer disc containing confidential details of 5,000 employees of the National Offender Management Service, including many prison officers.

Justice minister Jack Straw was told that the disc, containing names, dates of birth, and National Insurance numbers, was sent from a testing centre in Tyne and Wear to EDS in Telford last summer.

Officials at EDS said it was only when an employee went to use it on July 2 this year that the company realised it had gone missing and informed the Prison Service.

Mr Straw’s Ministry of Justice was due to brief data protection watchdog Richard Thomas today on the progress of its inquiry into the latest embarrassing loss of personal details on a government computer disc.

The Prison Officers Association warned that its members’ security may have been compromised and called for the ministry to terminate the contract with EDS, which was once Shropshire’s largest private sector employer until losing its inland Revenue IT support contract to Capgemini and Fujitsu.

The incident is the latest in a string of embarrassing Government data losses including the disappearance last year of two discs containing details of 25 million Child Benefit claimants.

Mr Straw said he was “extremely concerned” by the incident, but data protection minister Michael Wills sought to reassure staff whose details are contained on the disc.

“We believe the data is not in the public domain and therefore there are not significant risks to security. But obviously we take all steps necessary to mitigate any threat to personal safety.”

POA general secretary Brian Caton warned that the investigation announced by the Government may be “too little, too late”.

He said: “If anyone in authority has deliberately tried to cover up the loss of this data, I would hope they do the decent thing and resign. If not, Jack Straw must take the appropriate action.

“I would hope that the Government terminates the contract with EDS immediately following their deliberate act of withholding information and placing at risk thousands of prison service staff.”

No-one from EDS was available for further comment on the situation today, but shadow justice secretary Nick Herbert said: “This latest incident in the Ministry of Justice – the department responsible for data protection – makes a mockery of the Government’s claims to be improving data security and strengthening departmental accountability.

“It is not good enough for the Justice Secretary to sidestep these issues. He must take responsibility for his department.”

By Carl Jones