ENGLAND - April 27, 2008 - The Ministry of Defence's 'private' police force is using wide-ranging powers to stop and search thousands of tourists and other suspects, it can be revealed.

Armed street patrols, who are not required to identify themselves as MoD officers, are questioning people queuing for boat trips on the Thames or having their photograph taken in front of Big Ben.

Officers - who are routinely armed with sub-machine guns - say they are targeting those who match "certain profiles or behaviors" to deter terrorist attacks.

Their uniforms make them virtually indistinguishable from other police forces, but unlike regular officers, who are overseen by the Home Secretary and civilian police authorities, the MoD patrols are "under the command" of the Defence Secretary and a committee of civil servants.

Their normal role is to guard military installations and to investigate crimes on the 'defence estate'.

But the 3,500 officers are now able to carry out street searches after they were given extra powers under anti-terror laws.

They are also regularly being called in to provide backup for regular police officers.

Last night, senior politicians expressed "surprise and concern" about the increased public role.

Commons Home Affairs Select Committee chairman Keith Vaz called for an urgent investigation.

He said, "I will be asking the Home Secretary to clarify what these officers are doing, whether they are fully qualified to do this work and how much scrutiny they are under."