Changes to visa rules could lead to hundreds of UK doctors leaving the NHS each year, leading medics have warned.
The British Medical Association (BMA) said imposing new recommendations on visa rules from the Migrations Advisory Committee would be a "completely obstructive move".
UK medical graduates from overseas and international medical graduates are "essential" to the NHS workforce, said Dr Mark Porter, chair of council at the BMA..
In a letter to Immigration Minister James Brokenshire, the union said imposing a £1,000-a-year immigration skills levy for firms for each skilled migrant they recruit from outside Europe could also lead to a hefty bill for the NHS - the BMA estimates that the health service would have to fork out at least £3.5 million a year.
Meanwhile the recommendations could also mean that students from overseas who have obtained a UK medical degree will be last in line to get a job, the BMA said.
Dr Porter said: "UK medical graduates from overseas, and international medical graduates are essential members of our medical workforce and the NHS is dependent on them to provide high-quality, reliable and safe services to patients.
"This would be a completely obstructive move at a time when the NHS is facing unprecedented pressure and huge staff shortages, with rising concerns that junior doctors will leave the NHS after the Government's imposition of a new, unfair contract.
"The Government must consider specific exemptions for the NHS in order to ensure we have the necessary workforce to provide patients with the care they deserve."