(Reuters) -The U.S. Department of Justice on Monday backed a Department of Transportation proposal to revoke antitrust immunity for the joint venture between Delta Air Lines and Grupo Aeroméxico, which allows the two carriers to coordinate on scheduling, pricing, and capacity decisions for U.S.-Mexico flights.

In a filing, the Justice Department supported the DoT's position, arguing that the alliance may be stifling competition.

"Competition is particularly valuable in the airline industry. It drives lower prices, better quality, and more of the services consumers want."

The alliance was granted antitrust immunity in 2016, allowing it to go beyond standard codesharing-selling seats on each other's flights.

However, in January, the DoT said it did not plan to renew the antitrust immunity after the Mexican government implemented changes regarding airport slots and operations at Mexico City's main airport.

Delta and Aeroméxico did not immediately respond to requests for comment.