“Though migrants are used to discrimination and harassment, these new revelations show how the treatment of legal immigrants by border control now has stooped to the lowest of levels,” the statement from the HSMP read. The group, which won a high-profile case against the government this year, said migrants who were in Britain under the HSMP visa were suffering at the hands of “overly zealous immigration officers” at some of Britain’s busiest airports like Heathrow, Manchester and Belfast.

“Our members complain that upon their and their families' return from trips abroad, they are harshly discriminated against by the immigration authorities, though they are fully legally entitled to re-enter the country to continue contributing to the British economy,” said Amit Kapadia, executive director of the forum.

It gave the example of Pooja Tandon, who was detained at Heathrow airport while returning from a holiday in Switzerland with her husband, child and parents. It quoted her as saying the immigration officer lectured them about “finding alternative employment” and about “the shifts we work and child care arrangements.”

“He then said he is detaining us for further enquiry and if he is not satisfied with it, then he will deport us,” although the family was let off with a verbal warning. Pooja Tandon added: “We are really shaken by this incident. We felt being treated like criminals. We pay our taxes and national insurance and all other bills, and are being threatened this way.”

In a second instance, a doctor who has been in Britain for a decade was questioned by an airport immigration officer about his using the state health service for the delivery of their son, when all tax-paying foreigners are entitled to the National Health Service. “The immigration official had no legal position to threaten, abuse and intrusively demand information about the sensitive and private medical care of a legal migrant worker,” the HSMP Forum said.

In a third case, an HSMP migrant was detained for a few days and was about to be deported to his country of origin because he was not working in his field of expertise, “when in reality HSMP visas do not have any such restrictions.”

“It is clear from these cases that Immigration Officers have tried to take the law in their own hand,” the forum said.