The deepening GP crisis in Northern Ireland could become "disastrous" after Brexit if European doctors cannot stay, the Royal College of GPs (RCGP) has warned.
The RCGP said EU doctors made up 11% of the GP workforce in Northern Ireland - twice as many as England (5%), while in Scotland and Wales it is 4%.
It believes that without EU doctors, millions of patients across the UK will be left with no GP.
Northern Ireland GP services are already in crisis, with a number of surgeries facing having to close their doors.
Thousands of patients have been relocated to surgeries outside their areas or are depending on temporary contractors.
Dr Grainne Doran, chair of the RCGP in Northern Ireland, stressed that local GPs needed to be protected in Brexit negotiations.
"General practice is facing serious workforce challenges at the present time. We have seen a number of practice closures in recent months and it is essential that actions are taken to support general practice and maintain services for patients," she said.
She added the high proportion of GPs affected in Northern Ireland was due in part to local students receiving their qualifications in the Republic.
"The freedom to study and work across the border must not be impeded post-Brexit.
"It is vital that this is a priority consideration for our future governments in the Assembly and in Westminster," she said.
Dr Tom Black, chair of Northern Ireland's GP committee for the British Medical Association, said local GPs were already facing a "phenomenal" workload and losing European doctors was unthinkable.
"A key element of our workforce plans is to retain the GPs that are already here," he said.
"We have the smallest workforce in the UK in terms of GPs per head of the population, the average GP here is now looking after 2,000 patients.
"That's a workload which is not consistent with good access and good quality of care. We already have a crisis in GP recruitment, it would make things even worse to lose the European doctors."
Calling the mood among his colleagues "sombre", he said that as older GPs retired it was proving "virtually impossible" to find younger doctors to replace them.
"This is going to leave between 5-10% of practices collapsing this year. We've already lost a quarter of the practices in Fermanagh in the first five months," he said.
"We expect to lose up to three quarters of practices in Fermanagh over the next two to three years."
Last week, Dr Black said that £120m of investment was needed for general practice, but reforms agreed last year by civil servants and the previous health minister were being delayed by the collapse at Stormont.
Addressing a conference in Edinburgh, the senior medic said that when 60% of doctors signed undated resignation letters they would vote this summer on a "plan B" to leave the NHS.
Asked about the progress, he said the total so far would not be announced, but warned: "A steady stream of undated resignations are coming in."