LONDON -- An urgent inquiry was underway in Britain on Sunday after a disc containing the personal details of 5,000 justice staff went missing in yet another embarrassing data loss blunder.

File photo shows a prison van transporting inmates from Lincoln jail. An urgent inquiry was underway in Britain on Sunday after a disc containing the personal details of 5,000 justice staff, including prison officers, went missing in yet another embarrassing data loss blunder. [Agencies]

Those affected are employees of the National Offender Management Service (NOMS), who may include many prison officers.

"We believe nearly all of this data related to financial information -- for example, invoices from Prison Service suppliers," said a Ministry of Justice spokeswoman.

"However, we believe there is also a limited amount of personal information on around 5,000 NOMS employees including their names, dates of birth, National Insurance numbers and employee numbers."

According to a letter obtained by the News of the World newspaper, which it published on Sunday, private contractor EDS told the Prison Service in July that the hard drive had gone astray. The missing disc was last seen in July 2007.

"I am extremely concerned about this missing data," Justice Secretary Jack Straw said in a statement, adding that he was only informed about it on Saturday.

He said he had "ordered an urgent inquiry into the circumstances and the implications of the data loss and the level of risk involved.

"I have also asked for a report as to why I was not informed as soon as my department became aware of this issue. My officials are also in touch with EDS as part of these processes. We take these matters extremely seriously."

The news is the latest in a series of revelations in the past year of government data security blunders, with the Ministry of Defence (MoD) last month admitting that more than 700 laptops had been lost or stolen since 2004.

Last November, the government admitted it had lost confidential records for 25 million Britons who receive child benefit payments, and in January, the MoD revealed that a laptop with details of some 600,000 people interested in joining the armed forces had been stolen from a naval officer.

And the interior ministry admitted Thursday that personal details relating to every criminal in England and Wales had been lost.

PA Consulting informed the Home Office earlier last week that a computer memory stick which also contained information about thousands of prolific criminals was lost by the contractor.

The memory stick contained data on all 84,000 prisoners in England and Wales, as well as information from the Police National Computer of around 30,000 people with six or more convictions.