American Airlines says the government is investigating whether ticket-distribution systems are violating federal antitrust laws.
American said Friday it received a civil demand for information from the U.S. Justice Department. An airline spokesman declined to release the document.
The airline is fighting with so-called global distribution systems over the way information about flights and fares is shared with travel agents. American wants to cut out the systems and deal directly with travel agents.
Last month, American sued Travelport Ltd., which operates some of the largest distribution systems, accusing it of monopoly tactics and retaliating against the airline by burying information about its flights.
Travelport and Orbitz Worldwide Inc., an online travel agent partly owned by Travelport, countered that American was trying to control ticket distribution to limit consumer choice and reduce competition. American pulled its flight listings from Orbitz in December as the dispute was beginning to heat up.
American, a unit of AMR Corp., settled a similar dispute with another online travel agent, Expedia Inc., and information about American flights can again be found on Expedia.