Theresa May is pressing ahead with a controversial scheme to force visitors from “high-risk” countries in Asia and Africa to pay a “security bond” of £3,000 before they are allowed into Britain.
Immigration groups have threatened legal action over a scheme they have condemned as discriminatory because it omits applicants from “white Commonwealth” countries.
But the Home Secretary, who has overseen a fall of one-third in net migration levels, believes the moves are an essential step to deter people from overstaying their visitor visas.
People would automatically forfeit the £3,000 if they failed to return home after their visas ran out.
A pilot scheme will be launched in November covering selected new arrivals from India, Pakistan, Bangladesh, Sri Lanka, Nigeria and Ghana, with an eventual view to covering all people coming from those countries.
Officials said they had been selected because of relatively high levels of abuse among visa applicants.
Critics have warned that the move could backfire, with other governments retaliating and asking British visitors to pay bonds before they are allowed into their countries.
They also say it would be impractical because it would require a new bureaucracy to enforce it.