However, the government made retrospective changes to the visa regulations in 2006 saying applicants had to show annual incomes of £40,000 and be younger than 32 years of age in order to qualify. A voluntary group known as the HSMP Forum, whose 49,000 members are mostly Indians but also include other Asians and Africans, claim they and their families are at risk because of the retrospective nature of the rules.

They say making the rules retrospective violates their human rights, a view backed the British parliament's Joint Committee on Human Rights, which has recommended that "those who had already been granted leave as a highly skilled migrant on the HSMP when the relevant changes took effect should be treated according to the rules which applied before those changes".

The migrants also cite Commission for Racial Equality (CRE) findings to claim it is harder for black and ethnic minorities (BME) to secure highly-paid jobs in Britain, which means many of those who are already in the country may not earn £40,000 a year. The CRE says the new rules favour European Union migrants over those from outside the EU region.

The Forum says 90% of its members - around 44,000 people who left well-paid jobs in India to settle and raise families in Britain - may have to leave if the changes are applied retrospectively. According to Forum Executive Director Amit Kapadia, up to 150,000 people may be at risk, when families are taken into consideration.

Chandrasekar Elangovan, executive committee member of the HSMP Forum, said he hoped for justice from the "highly respected UK judicial system".

"It is ironic that a government which boasts itself as champions of human rights around the globe is actually playing with the lives of thousands of skilled immigrants and their families by changing the rules retrospectively," he said.