Thousands of people in Northern Ireland are missing out on potentially lifesaving medical treatment across the border because of Brexit, a leading Belfast healthcare lawyer has said.
Under the EU's Cross-Border Directive (CBD), patients here have been able to avail of £14.1m worth of healthcare in the Republic over the last five years.
The scheme has been even more popular south of the border, with €47.2m (£40.3m) worth of healthcare provided to residents heading north for treatment over the same period.
The CBD allowed patients in Northern Ireland to obtain treatment in a European Economic Area country, paying up front but then being reimbursed by the NHS.
One key requirement is that the treatment must be available in the applicant's home country through state-funded public healthcare. Patients can also choose either a public or private healthcare provider when they are travelling for treatment.
When the UK left the EU on December 31 last year, the scheme ended.
A replacement scheme for patients in the Republic accessing private healthcare in Northern Ireland has been set up. However, no such replacement has been put in place here.
Critics of the scheme have argued that the NHS should not have to foot the bill for private healthcare in foreign countries when it does not routinely do this in the UK.
With soaring hospital waiting times in Northern Ireland, there have been calls for a replacement scheme to be set up here as soon as possible.
According to the latest figures, on December 31 last year, there were 105,159 patients waiting to be admitted to hospitals here - 16.2% more than on the same date the previous year.
Belfast-based healthcare and litigation lawyer Kevin Hegarty said more needed to be done to ensure patients did not miss out on vital treatment.
"The issue is that, given that patients no longer have the option of going to another EU state for treatment and recouping the costs from the NHS, the already long waiting lists are likely to get worse in time. Patients who cannot afford the private care will simply have no option but to wait and wait," he added.
"In that sense, Brexit has adversely impacted an already challenging situation for many patients in Northern Ireland."
He said that as well as additional funding, more strategic cross-border co-operation was needed between the two governments, the Republic's health service and Stormont's Department of Health to get a new healthcare agreement in place.
"What has been put in place by the Irish government has not been replicated by the Executive. The longer this is left without a new scheme being introduced, the more detrimental the impact will be on the health and lives of patients across Northern Ireland," Mr Hegarty added.
The Department of Health said transitional arrangements were in place to protect patients "in prescribed circumstances, allowing them to complete their treatment and to seek reimbursement".
"Historically, there has been significantly more use of the cross-border healthcare scheme in Northern Ireland than any other part of the UK and there is interest in the continuance of a similar scheme," it said.
"Setting up a replacement for the scheme with some or all of the EU member states, European Free Trade Association countries and Switzerland would take time to negotiate and operationalise and would bring additional costs in future years.
"Departmental officials are considering the policy options to the principles of the CBD in this post-EU exit environment and will consider any resulting consultation and legislative requirements."