The Prime Minister has been accused of refusing to ease visa restrictions on skilled workers to enable more overseas doctors to work in the NHS.
Health service bosses warned that limits on the number of visas issued to doctors from countries outside the European Economic Area were contributing to rota gaps and delays in patients receiving care.
NHS Employers said there had been 400 blocked visas since December.
The London Evening Standard reported that Jeremy Hunt, the health secretary, and Amber Rudd, the former home secretary, had urged Mrs May to lift the quota for cases such as doctors, while Greg Clark, business secretary, wanted more exceptions for companies facing shortages of specialist skills.
The issue of visa restrictions on NHS staff came to a head last month when 35 NHS trusts accused immigration officials of jeopardizing patient safety by blocking visas for about 100 Indian doctors who had been given jobs in the health service.
The Financial Times reported with EU migration falling in the wake of the Brexit vote, there is growing demand for skilled workers, especially in the NHS.
However, non-EU visas are tightly limited under the government’s policy of cutting net immigration to “the tens of thousands” each year.
There is an annual limit of 20,700 Tier 2 visas for highly skilled workers. If the monthly total is exceeded, which has occurred in all of the past six months, professionals are turned away.
A spokesperson for Mrs May said the visa system was being monitored by the government. “It remains essential that we have control in our immigration system and that it works in the national interest.
“We are monitoring the situation in relation to visa applications for doctors including the monthly limits through the Tier 2 route. Around one-third of places go to the NHS.”
Jonathan Ashworth, shadow health secretary, said it made no sense for the government to turn away trained doctors and said the visa rules were not working in the interests of NHS patients.
“More than 100,000 NHS posts are now unfilled and vacancy rates for nurses and doctors are rising year on year, yet the government is refusing visas for trained staff from overseas.”