BANKS have begun running unprecedented immigration checks on customers to help Ministers track down and deport thousands of illegal migrants.
The Home Office said high street giants had begun verifying the immigration status of savers behind 70million accounts.
The Government believes as many as 6,000 illegal migrants could be booted out of the country as a result.
New legislation was introduced at the start of the year to impose the duty on banks and building societies.
The move comes just weeks after Border Force union officials claimed staff are so stretched they have “no way” of tracking down hundreds of thousands of illegal immigrants working on the black market.
They panned the Government for effectively outsourcing immigration enforcement work to private companies and landlords who face fines unless they check whether tenants have a right to be in the country.
In a statement new Immigration Minister Caroline Nokes said: “These new measures are part of our commitment to make it more difficult for people with no right to live or work in the UK to remain here.”
She added: “This will not affect those who live in the UK legally but we must be firm with those who break the rules as illegal immigration impacts the whole of society.”
Campaigners last year panned the crackdown when the proposals first emerged.