BBC: The Home Office has admitted illegal immigrants have been mistakenly cleared for jobs as security staff.
Ministers have ordered new checks to be carried out on hundreds of thousands of people vetted by the Security Industry Authority over the past three years.
The Home Office says the SIA did not check applicants were entitled to work in the UK before granting licences.
The Tories said the system was "not fit for purpose" but the government said the new checks had "strengthened" it.
According to the Sunday Mirror, illegal immigrants are working at airports, ports and the Metropolitan Police.
The newspaper claimed 5,000 illegal immigrants were estimated to have been employed in posts such as security guards and bouncers. Security staff employed illegally (more)
Mark Alexander
