Legislation has been approved in the US that could block Norwegian Air’s plans to launch transatlantic flights.
The airline is currently waiting for a permit from the US Department of Transportation, but officials fear it could "dodge international labour rules" by operating from Dublin.
The new rules proposed by the US House still need Senate approval before becoming law, but if they are approved Norwegian could be stopped from serving the US.
Some of Europe’s biggest unions have strongly opposed the airline’s plans to operate from its Irish base in Dublin.
They say if a licence is granted the airline could hire cheap Asian workers which would create "unfair competition with EU and US carriers" and "threaten to degrade labour standards" both in Europe and the US.
"Congress has a responsibility to make sure that US airlines do business in a fair marketplace and that the US government’s transportation funds don’t hand an advantage to foreign airlines that try to cheat the system," said Captain Lee Moak, president of the Air Line Pilots Association.
"We urge the US Senate to support the US House position and send a clear signal that Congress is committed to ensuring US airlines and their employees do business on a level playing field."
But Norwegian says any accusations of low wages and lack of safety are "slanderous."
It claims it already employs more than 300 US cabin crew in Fort Lauderdale and New York, and is currently recruiting New York-based pilots for its 787 Dreamliner operation.
It says its American employees say their wages and benefits are better than counterparts at US airlines.
