United States secretary of commerce Wilbur Ross has found in favour of United States-based manufacturer Boeing in a dispute over aircraft sales.

Ross ruled Canada-based Bombardier received government subsidies and sold its C-Series jets below cost price in the US, a step likely to lead to tariffs of more than 200 per cent on the plane.

The move affects 100- to 150-seat large civil aircraft from Canada.

“This decision is based on a full and unbiased review of the facts in an open and transparent process,” said secretary Ross.

“The United States is committed to a free, fair, and reciprocal trade and will always stand up for American workers and companies being harmed by unfair imports.”

The fight, which has contributed to escalating trade tensions between the US and Canada, stems from a 2016 sale of 75 C-Series jets to Delta Air Lines.

Boeing claims Delta paid $20 million per plane, well below an estimated cost of $33 million and what Bombardier charges in Canada.

As a result, the commerce department determined that exporters from Canada sold 100- to 150-seat large civil aircraft in the United States at 79.82 percent less than fair value. 

No planes have yet entered the United States.

In the UK, where Bombardier manufacturers wings for the planes in Northern Ireland, the move was branded political by the Unite union.

“More than 50 per cent of C-Series components are sourced from the US, where the supply chain sustains 22,000 US jobs,” added Unite assistant general secretary Steve Turner.

“The economic impact of these tariffs would be felt in communities on both sides of the Atlantic.”

The inquiry now moves to the United States international trade commission, which will examine if the dumping and subsidies caused injury to Boeing.

It is expected to make a final decision in February 2018, which would trigger the duties.

The petitioner in the case, Boeing, does not currently offer a rival product to the Bombardier C Series.

There is more information on the US department of commerce decision here.