The Ministry of Defence (MoD) has given hundreds of security passes allowing access to its head office to private contractors, the Government department has said.
UK arms manufacturer BAE Systems and US giant Lockheed Martin both have passes that allow cardholders to go in and out of the Whitehall buildings.
The figures released under the Freedom of Information Act reveal that well over 1,000 "active contractor passes" were given out for offices around the country, while 565 "could readily be attributed to contractors providing direct support to our London buildings".
Some of the passes were for IT workers and other support staff not relating to weapons manufacturers, the MoD said.
As of the start of December, BAE Systems had 16 passes, Lockheed Martin had four, missile specialist MBDA had five, and Qinetiq, the research company, had 12.
The MoD provided details of just 40 of the passes for the department's head office, citing national security and administrative costs as reasons why more information could not be released.
The figures correspond directly to a similar request in 2007 made by Liberal Democrat MP Norman Lamb.
Since then, the numbers of passes have been reduced. For example, BAE Systems had 38 in January 2007 and Qinetiq had 35.
The MoD said the contractor passes were valid for one year from the date of issue, and the head office access cards gave access to the Main Building, the Old War Office and St George's Court, although the holder "may be limited to certain areas within those buildings".
A spokesman said: "We have strict security procedures in place at MoD establishments and passes are issued only to individuals who have been security checked. Non-MoD personnel who need access to the MoD Main Building for meetings or other business are issued with temporary passes and escorted by a member of MoD staff at all times."
