Government ministers ordered the increased security checks after learning the Security Industry Authority did not determine whether those individuals were entitled to work inside Britain's borders, The Sunday Telegraph reported.

The revelation of a loophole in the authority's immigration regulations came in the wake of media reports showing a growing number of illegal immigrants work in significant security roles.

In one case, an illegal immigrant reportedly had even been providing security for Prime Minister Gordon Brown's personal vehicle.

"What is extraordinary about this latest Home Office fiasco is that we have been through this before," Shadow Immigration Minister Damian Green said. "Last year the Home Office discovered it was employing illegal immigrants as cleaners in the Immigration Department itself."

A Home Office spokesman told the newspaper future background checks will not be limited to checking applicants for criminal records.