There has been a sharp drop in the number of nurses registering to work in the UK since the EU referendum, figures suggest.
Last July, 1,304 nurses from the EU joined the Nursing and Midwifery Council register.
That compares with just 46 in April this year, a fall of 96%.
The Health Foundation, which obtained the figures from the NMC, said they should act as a "wake-up call" as the fall could compromise patient safety.
The think tank said the NHS was already struggling with nurse vacancies and, without this supply line, shortages could get worse.
In May, research by the Royal College of Nursing found one in nine posts in England was vacant.
'On the brink'
Anita Charlesworth, director of research and economics at the Health Foundation, said the fall could not be more "stark".
"Without EU nurses, it will be even harder for the NHS and other employers to find the staff they need to provide safe patient care.
"The findings should be a wake-up call to politicians and health service leaders."
Shadow health secretary Jonathan Ashworth said: "Theresa May's weak and unstable government has pushed NHS services to the brink, and it is patients who will pay the price.
"Our health service has always relied on the contribution of overseas workers, yet these staff are being forced out by this government's neglect and disregard.
"The Tories are overseeing an unforgivable drain of talent out of our country, because of their chaotic attitude to the Brexit negotiations."