The Government has branded as "irresponsible, unfounded and damaging", attacks made against Ireland's employment and aviation laws by opponents to Norwegian Air being granted a permit by US authorities to fly between Cork and America.
The no-holds-barred riposte against accusations made against Norwegian Air International (NAI) and Irish aviation and employment law was lodged by top Department of Transport civil servant Fintan Towey, who's the director general for civil aviation.
His letter was sent to the US Department of Transportation ahead of a deadline for submissions before a decision is finalised on granting NAI a permit to fly to America.
NAI, a subsidiary of Norwegian Air Shuttle, is based in Dublin and has spent the past two years trying to secure its permit. Washington officials indicated last month that they intend to grant the licence.
But might come too late for NAI to commence flights from Cork to Boston in time for the summer rush. The airline also intends to launch a service between Cork and New York next year. Shannon Airport is also hoping to secure transatlantic services from NAI, and the airport has also officially backed the carrier's permit request.
Last week, US presidential hopeful Bernie Sanders lent his weight to the opposition campaign, claiming that allowing NAI to fly to the US could ultimately precipitate an industry change that would result in hundreds of thousands of jobs being lost in America and Europe.
Those claims were roundly dismissed by supporters of NAI.
Opponents to NAI also claim that it is trying to circumvent stricter Norwegian employment laws by being based in Ireland, and also questioned safety oversight. Those allegations have been strongly denied by NAI, the Irish Aviation Authority and other bodies.
Mr Towey told the US Department of Transportation that efforts to tarnish Ireland's reputation has been a serious affront.
He said that while the delay in awarding NAI a permit is unwarranted, the attacks against Ireland's laws and oversight is of greater concern.
"Of even more concern to the Irish Government are the potential implications this case is having for the reputation of Ireland and Irish aviation," he said.
"The very protracted decision making procedure has provided certain stakeholders opposed to innovation and new competition in the airline market the opportunity to make irresponsible, unfounded and damaging public statements about the standard of social and employment protection in Ireland and about the capability of the Irish regulatory authorities to effectively oversee the safety of NAI's operations."
He added: "Most offensive are the allegations that Ireland provides a 'flag of convenience' for airlines."
Mr Towey said there had been claims that NAI's employment practices would risk undermining labour standards in the aviation sector. "However, these are misplaced and misinformed fears," he claimed.
"Airlines across the globe have used multiple crew bases and have also used third parties to meet some of their human resource needs for many years." A final decision on NAI's permit will be made shortly.