The warning comes after GP leaders at the Northern Ireland LMCs conference in March voted to press ahead with the 'nuclear option' - plans to collect undated resignations from practices.
A steady stream of practices have sent in undated contract resignations over the past three months, with GPC Northern Ireland leaders planning to lead a mass resignation once 60% of practices take part.
GPC Northern Ireland chair Dr Tom Black told GPonline that he hoped for 'solidarity and unity of purpose' from other UK GPs at the UK LMCs conference in Edinburgh later this month.
GP practice closures
He warned that Fermanagh, in Northern Ireland's Western LMC area, had lost a quarter of its practices already this year, and more are facing a struggle to survive. The Derry GP predicted at the Northern Ireland LMCs conference in March that 6% of the 350-odd practices in the country could go under in 2017.
Dr Frances O'Hagan, from the Southern LMC, told GPonline at the LMCs conference in March that she feared many practices would not survive long enough to take part in mass resignation.
Speaking to GPonline today, the Armagh GP warned that Portadown was the major focus of concern in the Southern LMC area.
'Our biggest problem is Portadown. One practice has closed and has been taken over by the trust – if any one of the others that are struggling go under, it could have a domino effect and take the whole town under with them. If one goes it won’t just be one - it will take everybody with them.'
She said it was impossible to say accurately how soon this could happen, but warned that closures were coming 'out of the blue' in Northern Ireland, even in areas such as Belfast where it had been assumed that practices were more stable.
Dr Black said: 'The undated resignations are still coming in steadily but the smaller practices particularly single handed are coming in quicker. 'This is a big legal decision for practices and is slower to resolve for larger partnerships. The members will decide if we ever reach 60% but it will take some months - remember they stay active for two years as per our conditions.
'Obviously as we continue to have practice mergers, collapses and closures the absolute number required will decrease. We have already lost more than a quarter of the practices in Fermanagh so far this year.
'The practices aren't coping with the government situation as there isn't a budget and so we have no GP rescue plan. The younger GPs are refusing to commit to practices - and who could blame them - and the older GPs are looking to retire early, and who could blame them.
The UK government has said it will step in from the end of June to set a budget for Northern Ireland if no government has been formed by that stage.