Speaking from Montreal, where he toasted the trade verdict over champagne with Bombardier counterpart Alain Bellemare, Airbus Chief Executive Tom Enders said the unexpected decision to block U.S. tariffs on the Canadian jet represented a victory for "sober business."

"Nothing is sweeter than a surprise - a surprise victory," Enders told Reuters in a telephone interview.

A U.S. agency voted 4-0 to reject proposed duties on Bombardier's CSeries, dismissing Boeing's claim that it had been harmed by the sale of jets at low prices to Delta Air Lines.

The ruling came as Bombardier awaits approval to sell the money-losing program to Airbus, which would assemble U.S.-bound CSeries jets in Mobile, Alabama.

"I am happy that they decided like that. It shows that sober business is still prevailing and it does not change our project; we will go ahead full throttle," Enders said.

"The single largest market for the CSeries - as also for the (larger mainline) single-aisle - is the U.S. and it cannot be wrong to have a strong position in the U.S."

Airbus began producing some single-aisle A320-family jets, which compete with Boeing's 737, in Mobile in September 2015, expanding its footprint beyond Europe and China. It plans a second line at the same plant for CSeries production.

Boeing had argued that Bombardier dumped CSeries planes to Delta at prices below the cost of production, adding a new layer to existing trade friction between Boeing and the U.S. carrier.

"I never heard of a good strategy that was conducted aggressively against one's own customer and that is what I would take away from that. I don't think that's the way to do business," Enders told Reuters.

Boeing said it disagreed with Friday's trade ruling and would review it when further details became available.

(Reporting by Tim Hepher; Editing by Tom Brown and Richard Chang)