United Continental Holdings on Monday said it would cut up to 500 jobs at the Houston headquarters of Continental Airlines, which merged last year with United Airlines.

The cuts would be management and salaried positions. United Continental has about 6,000 such jobs and more than 80,000 employees worldwide.

Spokeswoman Julie King said some employees had already accepted voluntary exit incentives and that the total number of job cuts could be less than 500.

It's difficult to determine the exact number of affected employees, because the process is tied to the needs of each department, King said.

Chicago-based United bought Houston-based Continental last year for $3.17 billion in an all-stock transaction.

Headquarters for the merged company is in Chicago, but the airline has said it would maintain a significant corporate presence in Houston, where Continental Airlines was headquartered..

The combined airline is integrating its largely unionized work force. Chief Executive Jeff Smisek told employees when the merger was announced last year that there would be some reductions in the salaried and management workforce at both companies.

He said the rank-and-file staff would see little impact on their numbers.

Shares of United Continental were up 3.7 percent at $26.61 on the New York Stock Exchange.

(Reporting by Kyle Peterson; Editing by Steve Orlofsky)