A union has claimed a bitter trade dispute between aerospace manufacturers Bombardier and Boeing could cost thousands of jobs in Belfast.
Canadian aerospace giant Bombardier, which employs around 4,500 people in Belfast and accounts for 10% of Northern Ireland's manufacturing exports, is facing significant costs in a spat with US aeronautics powerhouse Boeing.
The dispute centres over Boeing's allegations that Bombardier received subsidies allowing it to sell its CSeries planes at below-market prices. The US Department of Commerce is expected to announce a decision on whether to impose duties against Bombardier on September 25.
It's understood concerns were raised over the dispute by Prime Minister Theresa May in a phone call with US President Donald Trump.
Unite said it had been briefed on the action and said the dispute could put the the future of the company's Belfast operations in serious doubt.
Davy Thompson, from the union, said Bombardier could be hit with "punitive fines, threatening the future of the Bombardier site in Belfast".
"At present 1,000, or about 25%, are employed on CSeries production here but in four years’ time that number is expected to rise to 60% of jobs onsite. Bombardier is the largest private sector employer in Northern Ireland these jobs are vital to our economy and sustain many times more in the wider supply chain in the UK and Ireland."
The union has said it is looking to engage with government and unions representing Boeing workers to try and alleviate the threat posed. Mr Thompson said that as Mr Trump could not directly intervene, Mrs May should go straight to the head of Boeing.
"Bombardier benefited from state investment from the UK, Canada and from Invest NI all of which was entirely lawful and legitimate – a fact that the UK government should clarify," Mr Thompson added.
"Boeing’s attempts to link this public investment to the allegation of unfair competition are unsustainable; indeed, in the case of the sale of planes to Delta airlines which has been raised, Boeing did not even make a bid."
He added: "The UK government is the second largest purchaser of Boeing products. These present ample leverage to end this damaging course of action.
“Local politicians have a vital role to play as well. In the absence of a functioning Executive both leading parties need to find a way to be relevant to what is the greatest jobs threat facing Northern Ireland in a generation. Unite for our part will leave no stone unturned in our quest to safeguard these jobs.”
Bombardier has said the C-Series project was "critical to its long term Northern Ireland operations".
"We are responding to the petition proceedings and will not speculate on impact on our Belfast site should the Boeing petition be successful," the company said.
Boeing said it was seeking "to restore a level playing field in the US single-aisle airplane market".
"Boeing had to take action as subsidised competition has hurt us now and will continue to hurt us for years to come," the company said in a statement.
"This is the normal course of action for addressing instances where a competitor is selling into the US market below cost, and we will let the process play out.
"We believe that global trade only works if everyone plays by the same rules of the road, and that's a principle that ultimately creates the greatest value for Canada, the United Kingdom, the United States, and our aerospace industry," the company added.