The number of nurses and midwives coming to work in Britain from Europe has plunged by 89% since the UK voted to leave the EU, figures have revealed.

The sharp fall coincided with a sudden increase in qualified European medics leaving the Nursing and Midwifery Council’s (NMC) register: from 2,435 in 2015-16 to 4,067 in the last year – a rise of 67%.

The NMC data, released on Thursday, also shows a third worrying trend relating to the NHS’s already shortstaffed workforce – that the number of UK-trained nurses and midwives leaving the register rose by 11%, from 26,653 in 2015-16 to 29,019 last year.

Health union leaders said the trends were alarming and constituted “a double whammy for the NHS and patients”. The NHS is already short of an estimated 40,000 nurses across the UK and 3,500 midwives in England alone.

“These dramatic figures should set alarm bells ringing in Whitehall and every UK health department. [They] represent a double whammy for the NHS and patients”, said Janet Davies, the chief executive of the Royal College of Nursing.

The figures are the latest evidence that Britain’s decision last year to leave the EU has led to more staff from EU countries quitting and fewer choosing to pursue their careers in the UK.

An average of 1,966 nurses and midwives from Spain joined the register every year between 2012 and 2016. However, that fell by 95% to just 104 people between October 2016 and September 2017.

Similarly, the number of health professionals from Romania joining the register has dropped from 1,604 a year during those four years to only 216 last year. There has also been a dramatic drop in the numbers coming to work from Italy (1,325 down to 187), Portugal (1,127 to 73) and Poland (305 to 34).

Separate figures the NMC published in July showed that the number of nurses and midwives leaving the register outstripped the number joining it for the first time. And in September NHSA Digital disclosed that almost 10,000 EU doctors, nurses and support staff had quit the NHS in England since the Brexit referendum.

“Far from delivering the staff needed to keep patients on wards safe, nurse numbers are now in fact falling in our NHS. It’s staggering that numbers are falling when all the evidence shows we need more nurses in the NHS, not less”, said Jonathan Ashworth, the shadow health secretary.

Siva Anandaciva, the chief analyst at the King’s Fund health thinktank, said the falls in nurse numbers were deeply worrying given the need to maintain patient safety across the NHS.

“While the government’s recent commitment to increase nursing training places is welcome, training nurses takes many years and will not meet the short-term needs of the NHS or its patients,” he added.