Trade union leaders in the United Kingdom have welcomed possible Chinese interest in a Canadian passenger jet－the Bombardier C Series－with thousands of jobs at an aviation factory in Belfast possibly depending on such a deal.

Parts of the aircraft are made in Northern Ireland before planes are assembled in Quebec, Canada. But that production was threatened when United States aviation company Boeing objected to Bombardier's sale of 75 aircraft to Delta Airlines.

Boeing argued that Bombardier received unfair state aid from the governments of Canada, Quebec, and the UK. This week, the US Department of Commerce agreed with Boeing and made a preliminary decision to impose import duties of 219 percent on imports of the jets.

The UK and Canada have both said they will fight the US decision but Bombardier has been looking for new business in China as well.

Marc Meloche, head of structured finance at Bombardier Commercial Aircraft, said on Tuesday that the company hopes to sell aircraft in China.

"Bombardier is talking to all three big Chinese airlines, as well as many regional players and startups," Meloche told Reuters. "All are very interested in the Bombardier C Series."

Meloche said he was optimistic that deals could possibly be announced during the visit of Canadian Prime Minister Justin Trudeau to China later this year.

Bombardier said the new import duties imposed by the US were absurd and divorced from reality and would triple the price of any C Series sold in the United States, taking it to $61 million.

Canadian Foreign Affairs Minister Chrystia Freeland said the move was clearly aimed at eliminating Bombardier's aircraft from the US market.

US carrier Delta is Bombardier's largest client and was responsible for 75 of the total number of 360 orders placed for C Series aircraft since the CS300 and CS100 models entered service last year.

Bombardier employs 4,500 people in Northern Ireland, making it the largest private-sector employer.

"The C Series program is critical to the long-term future of our Northern Ireland operations," a Bombardier spokeswoman said.

Owen Reidy, assistant general secretary of the Irish Congress of Trade Unions, said the effect of job losses numbering in the thousands would be devastating for the economy, and that orders from China and elsewhere could provide a lifeline to Bombardier in Belfast.

Davy Thompson, branch officer for Bombardier at trade union Unite, said he was "very encouraged" by the news that Bombardier was closing in on deals in China.

UK Defence Secretary Michael Fallon said the moves by Boeing and the US could jeopardize Boeing's chances of securing future defense contracts with Britain.

The dispute between the US and the UK comes as Britain prepares to leave the European Union. While the UK may not be in a position to secure EU support for its position in the dispute, the government of Ireland might be in a better position. It could argue for EU intervention by saying that economic stability is vital for the whole island of Ireland, not just Northern Ireland.