The Conservatives say they will make it easier for doctors and nurses from around the world to work in the UK after Brexit, if they win the election.
The party would introduce an "NHS visa" as part of a promised "points-based immigration system".
But Labour said the policy was "full of holes," with nothing to say about low-paid nurses and other hospital staff.
And the Royal College of Nursing said "more ambitious" plans were needed to address NHS staffing shortages.
The Conservatives plan to end free movement of workers from EU countries when the UK leaves the EU - something they have promised will happen on 31 January if they are returned to power on 12 December.
The party would introduce a "points-based system" for migrant workers from EU and non-EU countries.
It has yet to spell out in detail how this will work - but it has announced that extra points will be awarded for coming to work in the NHS.
The cost of applying for a visa would also be reduced from £928 to £464 for medical professionals, and they would be guaranteed a decision within two weeks, under Tory plans.
Those granted an NHS visa would also be allowed to pay the annual £400 compulsory health insurance charge out of their salary.
Speaking during a campaign visit to the East Midlands, Prime Minister Boris Johnson said the proposals would make it easier for "talented" medical staff to get visas.
The Conservatives have already announced a fast-track visa route to attract specialists in science, engineering and technology.
They have also previously said they will scrap the cap on the number of skilled workers, such as doctors, from the EU and elsewhere, after Brexit.
The party is considering scrapping the minimum salary requirement of £30,000 for skilled migrants seeking five-year visas.
When asked if there would be more people from overseas working in the UK under a future Conservative government, Home Secretary Priti Patel did not answer directly but said the public wanted "controlled immigration".
Finding staff from outside the UK to come to work in the health service is as important as ever.
But those who wish to do so are often surprised at the fees they have to pay for the privilege.
To address this, the Conservatives plan to halve the £928 visa cost for NHS staff and their dependents.
But the £400 surcharge to cover their healthcare costs if they are from outside the EU won't be reduced, nor will the levy paid by the NHS and other employers if they hire foreign workers.
So it may be a move in the right direction, but if the health service badly needs trained doctors, nurses and others from abroad, it might be asked why they should pay any fees for visas or healthcare?
The Cavendish Coalition, representing a range of health and care organisations, says any steps towards tackling the high vacancy rate are welcome, but by not covering social care the policy is not ambitious enough.
These groups want any incoming government to recruit and employ any necessary workers from outside the UK "without criteria".
The Royal College of Nursing said a failure to train enough nurses was forcing the NHS to "recruit overseas in the short-term".
RCN chief executive Dame Donna Kinnair said she wanted to see a fairer immigration system that valued skills and did not fixate on "arbitrary targets".
"But the devil will be in the detail and we cannot be satisfied by rhetoric alone," she said.
"There are tens of thousands of unfilled nursing jobs and we need more ambitious plans than this to address it."
She added it was "immoral and heartless" to continue to make nurses contribute towards "the same services they keep running" through the health insurance charge.
"It should be abolished, not spread out every month," she said.
Labour also attacked the lack of detail in the Conservative plans.
Shadow home secretary Diane Abbott said: "The Tories are tying themselves in knots over immigration. They use dog-whistle anti-migrant rhetoric but are forced to accept we need migrant workers for key sectors, not just the NHS, but many more besides.
"This policy is full of holes, with nothing to say about the nurses earning below their income threshold, as well as all the cooks, cleaners, hospital porters and others who are vital to hospitals, and nothing at all about their right to bring family members here.
"Labour's immigration policy is rational and fair and will prioritise attracting the people we need, and treat them as human beings."
Liberal Democrat home affairs spokeswoman Christine Jardine said that, even with the visa application costs reduced for medical professionals, the £464 charge still amounted to a "nurse tax".
More than 12% of the NHS workforce reported their nationality as not British, according to a report published last year.
The biggest group of foreign NHS workers are from the EU - 56 in every 1,000 - but, the report added, the number of new staff coming from the EU is falling, and that this decline particularly applies to nurses.
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