Plans by Norwegian to fly between Cork and the United States have come under fresh fire from US aviation unions.
And following last week's Brexit vote, the US unions are also asking that the airline not be given a similar permit that would allow a UK subsidiary to fly to the US from Britain.
The US Department of Transportation indicated in April that it intends to grant Dublin-based Norwegian Air International (NAI) - a subsidiary of Norwegian Air Shuttle - a permit to fly from Ireland to the US. But since then, the formal approval has stalled. It is believed the matter was raised last week by the Government with US vice president Joe Biden during his trip to Ireland.
NAI applied for its US permit over two years ago. It had been expected that following the Department of Transportation announcement in April, that the permit would have been secured by now.
But US aviation unions have now sought leave to submit new evidence that they claim lends further support to their efforts to prevent NAI from using Ireland as a base to fly to America. NAI had hoped to launch a service from Cork to Boston this year, and between Cork and New York next year.
The unions want to admit an article by former US Deputy Secretary of Transportation (DOT), John Pocari, claiming that granting NAI a permit would be inconsistent with the US-EU Air Transport Agreement (ATA).
NAI has based itself in Ireland to enable it to avail of the EU-US Open Skies agreement that allows any EU airline to fly from any point in the EU to any point in the US, and vice versa.
"NAI is requesting to launch a complex international airline operation that at its core challenges explicit provisions of the agreement, in particular those specifically designed to protect high labour standards for cabin crews on both sides of the Atlantic," Mr Pocari claimed. "Norwegian Air's plan is to have their Irish subsidiary hire crews under Singaporean or Thai law that allows them to fly without having to comply with the employment and tax laws of its Norwegian home country."
But Norwegian has dismissed those claims on a number of occasions. It has pledged that any crew flying on NAI's transatlantic flights would be either from Europe or the US.
The US aviation unions have also said that the Brexit vote means Norwegian's UK unit (NAUK) shouldn't get its permit from the US DOT. Norwegian already flies from the UK to the US, but does so using its own Norwegian air operator certificate.
They have urged the US DOT to suspend processing of NAUK's application "until the post-exit regulatory structure that will pertain to the grant of operating authorisations to UK carriers is determined".