STEWART AIRPORT – A new subsidiary of Norwegian Air Shuttle will begin offering low-cost flights between Stewart International Airport and Europe as early as next year.

Executives of the budget carrier announced their plan to open a base at Stewart on Monday in interviews with routesonline, an industry website, and The Wall Street Journal. A second new U.S. base is also being considered in Portsmouth, N.H., or Providence, R.I., as part of a trans-Atlantic expansion that some American airlines and their unions tried to prevent.

“This is for real,’’ said Orange County Executive Steve Neuhaus. “The county has been working with the Port Authority on this for six, nine months – it’s got a lot of moving parts - and we’re very confident we’re finally going to see the ‘international’ in Stewart International Airport.”

Representatives of the Port Authority, which operates Stewart, and Norwegian couldn’t be reached for comment Monday.

Neuhaus said he understands Norwegian will offer 21 flights a week between Stewart and England, Scotland, Ireland and Norway using Boeing’s new 737 Max. The airline is scheduled to take delivery of the planes, which have a single aisle and carry 189 passengers, in mid-2017.

Discussions have already been held, Neuhaus said, with Coach USA about providing custom bus service for Norwegian passengers to such tourist destinations as Woodbury Common Premium Outlets and New York City.

Boeing, he added, also intends to open a small maintenance facility at Stewart to service the planes.

“Another moving part is the expansion of the terminal to provide (U.S.) customs services, so domestic and international flights can be processed at the same time,’’ Neuhaus. “We really want to see that fast-tracked now.”

Lou Heimbach, chairman of the Stewart Airport Commission, said he had written Port Authority Chairman John Degnan and Executive Director Pat Foye to ask that funding for the terminal’s expansion be retained in the agency’s soon-to-be-revised capital plan. He said he was assured that construction, which has lagged behind schedule, would start next year.

“Norwegian represents a phenomenal leap forward for Stewart,’’ said Heimbach, who has been lobbying the Port Authority to bring more service to the airport. “Not everybody on those flights is going to want to go to New York, so I can see demand building for service from Stewart to other U.S. cities.”

Norwegian received final approval from the U.S. Department of Transportation on Friday for its new Irish subsidiary, Norwegian Air International, to expand service in the United States. The application, pending for three years instead of the usual months, was opposed by some American airlines and their unions. The AFL-CIO has already said it will ask Congress to reverse the decision.

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The Associated Press contributed to this report.