PARIS — Airbus, the European plane maker, plans to build its first assembly line in the United States in Mobile, Ala., in an aggressive foray into the world’s largest market for single-aisle airplanes, people with knowledge of the plan said on Wednesday.

The plan calls for an investment of several hundred million dollars in a plant on Boeing’s home turf that could eventually assemble dozens of Airbus’s popular 150-seat A320 jets each year. Details are expected to be announced as early as Monday, said the people, who spoke on condition of anonymity because the plan was still confidential.

In taking the plunge into the United States, Airbus is betting that American airlines, many of which have large fleets of aging jets, will be enticed to consider an A320 that was “made in America” over Boeing’s competing 737. By assembling the planes with nonunion American workers, and in using dollars, Airbus also stands to reduce production costs.

Globally, Airbus and Boeing split the market for single-aisle planes fairly evenly. But in the United States, Airbus holds a 20 percent share.