Military Police are conducting an urgent investigation into the loss of a hard drive believed to contain the personal details of up to 100,000 serving armed forces personnel, as MPs demanded a "cultural change" in the way Whitehall treats personal information.

The call followed the disclosure that Ministry of Defence (MoD) subcontractor EDS could not account for the whereabouts of the portable drive, which could contain passport numbers, dates of birth, names of next of kin and driving licence details as well as names and addresses.

A spokesman for prime minister Gordon Brown confirmed the investigation and described what had happened as "regrettable".

There was no comment on any implications for the government's ID card system, which faces increased political challenges following a series of government data handling blunders.

New defence secretary John Hutton is reported to have called for an examination of EDS' contract to see how it covers this type of breach of trust.

Tory shadow defence secretary Liam Fox said that the incident underlined the MoD's poor record in keeping sensitive and classified material secure.

"The loss of so much confidential information shows the reckless approach this government takes with our personal information," he said.

Tory MP Nigel Evans, chairman of the All-Party Parliamentary Group on Identity Fraud, said it was ironic that the loss was revealed during National Identity Fraud Prevention Week.

The loss of the type of data believed to be missing "will be music to the ears of fraudsters everywhere", he said.

"It is vital there is a cultural change across the public sector with all professionals aware of their responsibility to protect and manage personal data, " added Evans.

SNP defence spokesman Angus Robertson said it was "extraordinary that the MoD could allow this to happen again" on top of the loss of data on more than 500,000 potential recruits and their families, which was stored unencrypted on a laptop in a Royal Naval officer's car.

The MoD said it was informed on Wednesday by EDS that it was unable to account for a portable hard drive used in connection with the administration of armed forces personnel data. The loss was revealed by an audit the company was performing in compliance with the Cabinet Office data handling review.

Other recent data losses include four laptops containing details of more than 100 bankrupt company directors from the Insolvency Service in Manchester, details of nearly 18,000 current and former staff at Whittington NHS hospital by a firm providing payroll services, and a computer containing details of 5,000 prison and offender management staff, also by EDS.