The number of laptops and USB sticks containing classified and restricted data lost by the Ministry of Defence (MoD) since 2004, is much higher than first originally thought.

The figure actually stands at 658 laptops and 121 USB sticks, compared with the original figure of 347 given by the MoD. The discrepancy was discovered by Liberal Democrat MP Sarah Teather who raised questions over two contradicting parliamentary reports.

"It seems that this government simply cannot be trusted with keeping sensitive information safe," said Teather.

"It is frightening to think that secret MoD information can be lost or stolen. This shows a shocking degree of incompetence across the entire government," she added.

The MoD has previously said that any data loss is fully investigated but only 32 of the laptops have been recovered. It also raises questions over who pays for the investigation to retrieve the stolen data following the admission that the UK taxpayer is footing the £473,544 bill for the Metropolitan Police investigation to retrieve discs containing 25 million child benefit records, which went missing last year.

The revelation comes at a bad time for the MoD after it was forced to admit last week that another laptop containing sensitive information has been stolen, this time from the Adelphi Hotel in Liverpool.

Alan Bentley, vice president of Lumension Security, said: "The number of laptops stolen should not be a concern to the government or the public. It is the data that was on the latest stolen laptop, which is the only important yardstick for whether this latest incident is a problem for the MoD. As sensitive data becomes more and more of a target, it is imperative that Government departments know exactly what data is held on what device."

See also: MoD implements new data security measures