Norwegian Air has confirmed that the airline’s flights to and from Cork and Shannon to the US will continue to be re-routed via Dublin for the remainder of the summer.
A spokesperson for the company said the move was due to "the continued grounding of the Boeing 737 MAX by the European aviation authorities".
Norwegian Air explained that Cork is a seasonal route and the reduced availability of aircraft has led to the removal of Shannon services this winter.
In a statement, it said: "Customers travelling to and from Cork and Shannon are being re-accommodated on to different aircraft types between Dublin, New York and Providence to ensure travel plans can continue with minimal disruption.
"Customers are advised to arrange bus or rail travel to Dublin and can claim for their expenses with proof of receipt.
"Alternatively, customers have also been given the chance to rebook or receive a refund free of charge and we would like to sincerely apologise for the inconvenience caused."
A spokesperson for Shannon Group said: "The world-wide grounding of the 737 Max aircraft is having a serious impact for Shannon passengers.
"Proportionally, no other Irish airport has such a high level of activity operated by the 737 Max aircraft.
"At peak this aircraft type would have operated 13 weekly flights from Shannon to North America.
"We now estimate that the loss of these flights, which include this year's Air Canada service, will mean a loss of over 120,000 seats at Shannon in 2019 and as a result our overall passenger numbers will be down."
The Department of Transport, Tourism and Sport said that while the move was "obviously hugely disappointing", it understands that the issue arises due to the grounding of the entire Boeing 737 Max aircraft fleet by the Federal Aviation Authority in the US and the European Aviation Safety Agency.
In March, Norwegian Air temporarily deployed a Boeing 787-9 Dreamliner to operate US flights from Dublin Airport to support customers affected by the decision to ground its Boeing 737 MAX planes.
The move followed two fatal crashes in Indonesia and Ethiopia involving the same plane model.
In response to the instruction by the European aviation regulatory, the airline effectively grounded all its 18 MAX planes.
The Oslo-based company also stated it would seek compensation from plane maker Boeing for costs and lost revenue after grounding its fleet.