The Ministry of Defence has been accused of “shocking incompetence” after it was forced to admit that 747 laptops and 131 of its computer memory sticks have been lost or stolen in the past four years.

The latest admission is almost double the number of laptops the government department had already admitted to having stolen after a series of breaches of security.

The MoD also admitted that 26 portable memory sticks containing classified information had been either stolen or misplaced since January.

The Liberal Democrats condemned the latest security breaches, which happened despite a cross-Whitehall drive to tighten procedures, as evidence of incompetence.

Sarah Teather, Liberal Democrat MP for Brent East, said: “It seems that this Government simply cannot be trusted with keeping sensitive information safe.

“It is frightening to think that secret MoD information can be lost or stolen.

“How can they expect us to trust them to keep our personal information safe in their unnecessary and expensive ID card scheme?”

However, the MoD insisted that its policies were “generally fit for purpose”, and said all data losses were fully investigated.

At least three of the 26 laptops stolen this year contained information classified as “secret” and 19 had data which should have been “restricted”.

In January a Royal Navy computer was stolen that contained passport, National Insurance and driver’s licence numbers, family details and NHS numbers for about 153,000 people who applied to join the armed forces and banking details of around 3,700.

The breaches of data security by the MoD follow the exposure last year of a catastrophic failure to maintain privacy by HM Revenue & Customs when the department lost CD-Roms containing details of 25 million Britons.

The latest embarrassing details were disclosed by ministers in response to questions tabled in Parliament. Previously the MoD had confessed to 347 laptops being stolen between 2004 and 2007. But Defence Secretary Des Browne was forced to issue revised figures after “anomalies in the reporting process” were discovered.

The official total is now 658 laptops stolen, with another 89 lost. Just 32 have been recovered.

In a separate response, ministers said that 131 of the department’s USB memory sticks had been taken or misplaced since 2004.

Last month the MoD was heavily criticised by a review of its data procedures which warned that basic security discipline had been forgotten and there was “little awareness” of the danger of losing information.

But a spokeswoman for the department said today: “Any loss of data is investigated fully.

“The recent report on data losses by Sir Edmund Burton found that MoD policies and procedures are generally fit for purpose, but also identified a number of areas where MoD needs to do better in protecting personal data.

“MoD has developed, and is now working through, an action plan to address all of the report’s recommendations and bring the department’s handling of personal data to an acceptable state.”

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