The Ministry of Defence is launching a new inquiry after admitting to the loss of two more laptops containing unencrypted personal details.
The additional losses came to light during the investigation of the theft earlier this year of a laptop containing 600,000 peoples' personal details.
A Royal Navy laptop containing details of 500 people was stolen from a car in Manchester in October 2006 and a laptop was stolen from an army recruitment office in Edinburgh in December 2005, Defence Secretary Des Brown admitted.
"Our internal investigation has identified weaknesses in the application of MoD security procedures," Brown said.
The Ministry of Defence does not appear to be the most careless government department.
One hundred and sixty nine Ministry of Justice laptops have been mislaid -- lost, stolen or missing -- since 2001, while the Ministry of Communities and Local Government has mislaid 28 laptops in the same period.
Departmental minister Parmjit Dhanda told MPs, "The official data on each of the laptops was not encrypted because none of the information was classified." In an attempt to reassure MPs, he added, "Each laptop was password protected."