More than 650 laptops have been stolen from the Ministry of Defence (MoD) over the past four years, more than twice the number previously claimed.
And 121 USB memory sticks have been lost in the same time period.
Previously the MoD had confirmed that 347 laptops were stolen between 2004 and 2007 – defence secretary Des Brown said that figures were revised after the MoD discovered "anomalies in the reporting process".
The information was revealed after Liberal Democrat MP Sarah Teather tabled questions in parliament.
The exact figures for 2004 to 2008 are:
658 lost laptops, 32 of these were recovered.
121 lost USB sticks, including 26 this year, three of which contained information classified as "secret" and 19 with information classified as " restricted".
A recent report into the loss of a MoD laptop containing the details of 600,000 potential applicants to the forces found that the department is not treating information as a key business asset.
"Information risk is not being formally managed at executive boards across the Department, with a small number of exceptions," says the Burton Review.