US trade officials are expected to confirm massive tariffs on Bombardier planes Tuesday in a case that has inflamed relations between Washington and Ottawa.

The trade dispute stems from a complaint by US aerospace giant Boeing against its Canadian rival that found a receptive ear in President Donald Trump, whose "America First" agenda has included taking a tough line in matters of international commerce.

Boeing argues that Bombardier signed a deal to sell its new single-aisle CS 100 planes with a price tag of just $19.6 million each, far below the $33.2 million construction cost, and a pittance compared with the list price of $79.5 million -- though that amount is almost never paid.

Bombardier was able to underprice the jets due to $3 billion in unfair government subsidies, Boeing says.