United Airlines on Wednesday began charging passengers flying out of Los Angeles International Airport an additional $10, a fee the airline said is necessary to offset a $10 million increase in the rent charged by the airport.

United Airlines said that the rent increase, which was imposed on all airlines late last year, violates its long-term lease agreement with Los Angeles World Airports, which runs the airport. United, along with American Airlines and Continental Airlines, has sued the airport and 22 other airlines have filed a complaint about the rent increase with the Transportation Department.

For its part, LAWA says that it has absorbed the ballooning costs of security and said the rent hike is necessary if the scheduled improvements at LAX are to go forward.

The air travel industry trade group Air Transport Association has publicly criticized LAX for its increase in terminal rates, saying they were unfair to airlines and passengers alike.