More than 1,000 illegal migrants have been arrested following random swoops on tube passengers and pedestrians in London, Home Office figures showed last night.
The figures showed the joint exercises by the police and immigration service have become a regular weekday event in the capital with 235 operations mounted in the last 15 months.
Ministers have ordered the trawl for failed asylum seekers as part of their attempt to step up the return of illegal migrants to their home countries.
Last month’s asylum figures showed the number of failed asylum seekers removed from Britain fell by 18% compared with the same period in 2003.
The Home Office is to bring in powers stripping failed asylum seekers with young children of council accommodation and welfare benefits in an effort to step up the rate of removals.
The exercise, running since last May, involves immigration staff stopping anyone they consider to look or sound a possible illegal migrant, asking them about their nationality and to produce papers to prove their right to be in Britain.
Some of those stopped have been overheard speaking a non-European language.
The spot checks have been carried around “crime hotspots” and among passengers on the London Underground with the support of the British Transport police.
The figures showed that those arrested included 717 failed asylum seekers but thousands more people have been stopped and questioned by immigration staff using powers which the police are banned from using.
Des Browne, the immigration minister, in a Commons written answer published yesterday, defended the operation saying the use of immigration staff in public places was a legitimate activity to enforce the immigration laws.
“While immigration officers do not have the same powers as the police to stop and search individuals in public places, they may legitimately question people to determine their immigration status where there is reasonable suspicion that a person is an immigration offender,” he said.
But the Liberal Democrats protested strongly at the practice.
Mark Oaten, the party’s home affairs spokesman, said: “Trawling public places for failed asylum seekers is a clumsy attempt to shut the stable door after the horse has bolted.
“It is the job of the Home Office to keep track of asylum seekers and to remove them if they fail to win refugee status.”
He said that unlike some other countries, Britain did not have a history of randomly stopping thousands of black and Asian people to check whether they were illegal migrants.
“In order to catch 1,000 illegal immigrants, many thousands of law-abiding citizens will have been stopped on the basis of their skin colour and their accent alone,” he said.
“That is unacceptable and will cause real damage to race relations,” he added.