Britain recruited a record number of international nurses in the last financial year to plug hospital staffing shortages, with as many as 10% coming from so-called "red-list" countries where health staff should not be actively recruited.
Britain has long hired from abroad to staff its state-run National Health Service (NHS), and its vote to leave the European Union in 2016 meant the number of EU staff has dropped sharply in recent years.
In the year to March, nearly half of the 52,148 nurses, midwives and nursing associates who joined the British register were internationally educated, according to the Nursing and Midwifery Council (NMC). Nearly 3,500 came from Nigeria, which is on the the World Health Organization's safeguards list.
The two biggest international contributors to Britain's nursing workforce - India and the Philippines - are not on the red-list.
The WHO has warned that poorer countries are increasingly losing healthcare workers to wealthier countries, and has flagged concern over active recruitment in some countries.
Jim Buchan, senior fellow at the Health Foundation, said the numbers arriving in Britain from red-list countries, notably Nigeria and Ghana, had gone up markedly.
"The requirement of (WHO) member states is not to actively recruit from these countries, but what the data can't tell us is how these nurses have come to be on the UK register," he said.
Caroline Waterfield, director of development and employment at NHS Employers said hospital trusts and others who hire staff in England's NHS have been told to work only with agencies that are accredited, vetted and not operating in red-list countries.
"The bit which has always been a bit more tricky is if individuals apply themselves," she said.
The rules do not stop individuals based in red-list countries applying for jobs in Britain, and while an agency may not actively recruit them, community links to people already in the country might mean people apply more from certain countries.
Paul Wanyonyi Simiyu is a nurse, originally from Kenya, who came to Britain four years ago. Kenya is on Britain's "amber" list, meaning any active nurse recruitment has to be through a bilateral agreement Britain has with Kenya.
Despite that agreement, Simiyu estimates 90% of the recruitment of Kenyan nurses comes via direct applications to UK jobs, adding that there often aren't jobs for them in Kenya. He founded KenyanNurse to help train Kenyan nurses for English exams and advises them on how to process their registration.
"It's not against any international or national laws for me to tell a friend or anyone else, hey, there's a job somewhere overseas," he said.
On Friday Britain announced £15 million (about RM85 million) in funding to strengthen the health workforce in Kenya, Nigeria and Ghana, citing low staff numbers in their health systems and high unemployment among health workers.
Britain's health service has endured a tough winter, creaking under high demand, staffing shortages, strike action over pay and long waits for operations and ambulance visits.
It pledged in 2019 to have 50,000 more nurses in the NHS in England by next year, and health minister Steve Barclay said the government is on course to hit that target and would publish a new long-term workforce plan shortly. The Health Foundation estimates that NHS England has 43,000 nursing vacancies.
The drop in EU staff has helped fuel demand for more workers, with NMC data showing a 20% fall in health staff from the European Economic Area between March 2018 to March 2023.
Buchan said that the lower numbers of EU staff, domestic shortages and a lack of UK nurses in training meant further non-EU recruits would be needed to hit the target.
"The target itself has been a driver for international recruitment because it's the relatively quick fix way of getting nurses into the system," he said. "Will we have to carry on at high levels of international recruitment to try and fill vacancies in the short term? Yes we will."