Nurses from the EU face paying an annual £600 fee for their own health costs after Brexit in a move that will deepen the NHS staffing crisis, their leaders have warned.

The “immigration health surcharge” paid by migrants from outside Europe could be extended to people arriving from within the EU, the Home Office has admitted.

Families are already being “torn apart” by the charge, said the Royal College of Nursing (RCN), highlighting how nurses have been forced to leave their children abroad.

Evaline Omondi, from Africa – faced with paying £3,600 up front to cover three years of fees for two adults and four children – had to send her youngest children, aged six and eight, back to Kenya.

Now Janet Davies, the RCN’s chief executive, will tell its annual conference: “It could be about to get even worse. Ministers will not rule out extending this to European nurses once we leave the EU.

“The government must not put Spanish, Portuguese or Italian colleagues through the same after Brexit. We cannot afford to haemorrhage even more expertise.”

The NHS is currently short of at least 43,000 nurses across the UK – despite being boosted by a total of 140,000 staff from EU countries.

Under the surcharge, introduced in 2015, migrants must pay a £200 fee per family member for every year on their work permit, to cover possible NHS costs.

It will double to £400 later this year and last year’s Conservative election manifesto promised a £600 charge. Students would pay £450, instead of the current £150 – rising to £300 this year.

Brexit threatens life on the Irish border: in pictures Show all 15 1 /15 Brexit threatens life on the Irish border: in pictures Brexit threatens life on the Irish border: in pictures An abandoned shop is seen in Mullan, Co Monaghan. The building was home to four families who left during the Troubles. The town was largely abandoned after the hard border was put in place during the conflict. Mullan has seen some regeneration in recent years, but faces an uncertain future with Brexit on the horizon Reuters Brexit threatens life on the Irish border: in pictures A defaced ‘Welcome to Northern Ireland’ sign stands on the border in Middletown, Co Armagh Reuters Brexit threatens life on the Irish border: in pictures Mervyn Johnson owns a garage in the border town of Pettigo, which straddles the counties of Donegal and Fermanagh. ‘I’ve been here since 1956, it was a bit of a problem for a few years. My premises has been blown up about six or seven times, we just kept building and starting again,’ Johnson said laughing. ‘We just got used to it [the hard border] really but now that it’s gone, we wouldn't like it back again’ Reuters Brexit threatens life on the Irish border: in pictures Farmer Gordon Crockett’s Coshquin farm straddles both Derry/Londonderry in the North and Donegal in the Republic. ‘At the minute there is no real problem, you can cross the border as free as you want. We could cross it six or eight times a day,’ said Crockett. ‘If there was any sort of obstruction it would slow down our work every day’ Reuters Brexit threatens life on the Irish border: in pictures John Murphy flies the European flag outside his home near the border village of Forkhill, Co Armagh Reuters Brexit threatens life on the Irish border: in pictures Potter Brenda McGinn stands outside her Mullan, Co Monaghan, studio – the former Jas Boylan shoe factory which was the main employer in the area until it shut down due to the Troubles. ‘When I came back, this would have been somewhere you would have driven through and have been quite sad. It was a decrepit looking village,’ said McGinn, whose Busy Bee Ceramics is one of a handful of enterprises restoring life to the community. ‘Now this is a revitalised, old hidden village’ Reuters Brexit threatens life on the Irish border: in pictures Union Flag colours painted on kerbstones and bus-stops along the border village of Newbuildings, Co Derry/Londonderry Reuters Brexit threatens life on the Irish border: in pictures Grass reflected in Lattone Lough, which is split by the border between Cavan and Fermanagh, seen from near Ballinacor, Northern Ireland Reuters Brexit threatens life on the Irish border: in pictures Donegalman David McClintock sits in the Border Cafe in the village of Muff, which straddles Donegal and Derry/Londonderry Reuters Brexit threatens life on the Irish border: in pictures An old Irish phone box stands alongside a bus stop in the border town of Glaslough, Co Monaghan Reuters Brexit threatens life on the Irish border: in pictures Billboards are viewed from inside a disused customs hut in Carrickcarnon, Co Down, on the border with Co Louth in the Republic Reuters Brexit threatens life on the Irish border: in pictures Seamus McQuaid takes packages that locals on the Irish side of the border have delivered to his business, McQuaid Auto-Parts, to save money on postal fees, near the Co Fermanagh village of Newtownbutler. ‘I live in the south but the business is in the North,’ said McQaid. "I wholesale into the Republic of Ireland so if there’s duty, I’ll have to set up a company 200 yards up the road to sell to my customers. I’ll have to bring the same product in through Dublin instead of Belfast’ Reuters Brexit threatens life on the Irish border: in pictures A disused Great Northern Railway line and station that was for customs and excise on the border town of Glenfarne, Co Leitrim Reuters Brexit threatens life on the Irish border: in pictures Alice Mullen, from Monaghan in the Republic of Ireland, does her shopping at a former customs post on the border in Middletown, Co Armagh. ‘I’d be very worried if it was a hard border, I remember when people were divided. I would be very afraid of the threat to the peace process, it was a dreadful time to live through. Even to go to mass on a Sunday, you’d have to go through checkpoints. It is terribly stressful,’ said Mullen. ‘All those barricades and boundaries were pulled down. I see it as a huge big exercise of trust and I do believe everyone breathed a sigh of relief’ Reuters Brexit threatens life on the Irish border: in pictures A bus stop and red post box stand in the border town of Jonesborough, Co Armagh Reuters

In a written parliamentary answer, Caroline Nokes, the immigration minister, said EU citizens and their family members currently in the UK would not have to pay the charge after Brexit.

They would be “protected by the withdrawal agreement”, the minister said – although the agreement is not certain, because of disagreements over future customs rules and the Irish border.

Ms Nokes then said: “Future arrangements on immigration policy after the end of the implementation period are to be confirmed.”

She added, confusingly: “We will want to ensure that any decisions on the long-term arrangements are based on evidence and engagement.”

Ms Omondi, who will explain the harsh impact of the surcharge on her family to the Belfast conference tomorrow, said it was an “awful moment”.

“We could not meet the cost and my children had to move back to Kenya. A family who came together is now in pieces, scattered all over the place,” she said.

“I try to speak to them on the phone before they sleep, but it is hard with the time difference and my work so sometimes I don’t get to talk to them.”

Ms Davies will say: “When facing staff shortages in NHS and care, the UK has depended on professionals from around the world.”

Condemning the Windrush scandal for revealing “Britain being heartless, divisive and plain old nasty”, she will add: “It is shameful that families are being torn apart by this policy, too.”

But the Home Office said the surcharge had an important role to play, generating income that goes directly to the NHS.