Flights from Belfast to New York have been cut at International Airport, after a European funding package to protect the service was withdrawn.
The European Commission voted to block the funding package, which means flights will cease from early in January of next year.
The loss of the United Airlines service had been described by the airport’s Managing Director Graham Keddie as an “abysmal” decision.
“You could hardly get a worse example of process-driven madness. To block a support package for an airline that delivers direct access to the United States is almost beyond comprehension,” he said in a statement.
“This is a vital link for business and losing it will be a body blow to Executive Ministers who use it to promote Northern Ireland to would-be investors from the United States.
“We have worked tirelessly to safeguard the service, but Brussels took a different view, believing the support package gave United an unfair advantage over services from elsewhere.
“That, on its own, is bizarre as the package in no way competes or conflicts with competitors within the United Kingdom. The EU decision-making process is abysmal, biased and unfair and has resulted in the loss of this service.”
Economy Minster Simon Hamilton said that the Executive had acted to try and save the air route.
“The Executive did the right thing with its bid to save this key route. There was a risk to the flight and we stepped in to save it," he said.
"Faced with the same circumstances again, I would make the same decisions. All public money has been recouped with interest and we retained the route for a longer period.
"We were always aware of the potential of an issue around state aid compliance, but given the tight timescale to put a package of support in place, approval by the European Commission could not be sought in advance of agreeing a deal with United and it was our view, on balance, that given this was our only direct flight to the USA, state aid was not a factor.
" It is, therefore, deeply regrettable that unelected bureaucrats in Brussels have effectively scuppered this important flight for Northern Ireland."
The company United airlines released a statement outlining their response to developments.
"United will discontinue its service between Belfast and New York/Newark.
"The last departure from Belfast will be on 9 January 2017 and the last departure from Newark will be on 8 January 2017.
"We have regretfully taken this decision because of the route’s poor financial performance.
"We will contact customers with bookings for flights beyond those dates to provide refunds and re-accommodate where possible. We apologize for any inconvenience caused."