40,000 rejected migrants 'missing'

The Home Office admitted the illegal immigrants should have left the country more than six years ago but could still be here.

Officials have launched a trawl of the cases to try and find them and remove them from the country.

Every file will be checked against police and terror lists to see if they present a risk to the public.

The deeply embarrassing revelations are the latest scandal to hit Britain's immigration system in recent years.

Officials are still working through the cases of foreign prisoners who were not sent home after finishing their sentences, and the backlog of asylum claims. They admitted they had stopped actively looking for 85 former inmates who could not be found after a three-year search. These files will now be transferred to a "controlled archive".

Sir Andrew Green, chairman of Migrationwatch UK said: "Yet another skeleton in the Home Office cupboard. Tens of thousands of case files lying around and the true situation covered up for years on end. This is symptomatic of the utter chaos in the asylum and immigration system during the past ten years. Nobody in the private sector would get away with such a performance."

Details of the trawl were included in a letter to MPs from Lin Homer, chief executive of the UK Border Agency (UKBA). She told the Home Affairs Select Committee most of the cases were from before 2003 and there was "no formal record" of the immigrants leaving. In some cases, further action might not be possible, if the individuals cannot be found, she said.

"In the last few months we have begun the process of reviewing these files to consider if any further action is necessary or possible," she said. "Where further action is required it will be taken and any cases which may be considered as harmful to the public will be prioritised."

Three years ago, then Home Secretary John Reid said the immigration system was "not fit for purpose" after it emerged 1,019 foreign prisoners were released without being considered for deportation.