US Airways Group and American Airlines say their pending merger should win regulatory approval because their networks are complementary and out of more than 900 domestic nonstop routes, only 12 have overlapping nonstop flights.

But a study released Tuesday by the Consumer Travel Alliance says that the merger would eliminate connecting-flight competition between the airlines on 761 common connecting routes, and that the new American would be able to raise ticket prices on those flights.

The nonprofit consumer travel-rights group wants antitrust regulators to look at how the merger will affect competition on both nonstop and connecting flights. The study says 40 percent of American's connecting routes and 30 percent of US Airways' connecting routes have overlap.

"Real competition between network airlines takes place through connecting flights, where these two airlines compete now but will not after the merger," said Charlie Leocha, Consumer Travel Alliance director.

US Airways and the bankrupt American announced in February that they would merge to create the world's largest airline. The deal is expected to close before Sept. 30.

The consumer group gave examples of flights for which competition would be reduced:

Philadelphia to Albuquerque, N.M.: US Airways flies between the cities with a connection in Phoenix. American flies between them with a stop in Dallas.

Philadelphia to Little Rock: US Airways connects through Charlotte, N.C. American connects in Chicago.

Philadelphia to Reno, Nev.: US Airways makes a connection in Denver. American connects passengers in Dallas or Chicago.

"Philadelphia to Miami happens to be one of the 12 overlapping nonstop routes," Leocha said. After the merger, only American will fly nonstop to Miami.

US Airways disagreed with Leocha's assertions, saying the new American - with more than 6,700 daily flights to 336 destinations in 56 countries - "will strengthen communities nationwide through better service and travel to more destinations."

"Significantly, we plan to maintain current hubs of both airlines and expand service from those hubs, resulting in more choices for customers," US Airways spokesman Todd Lehmacher said.

"Unfortunately, Mr. Leocha overlooks several key facts - our competitors offer numerous options for travel, and consumers have continued to enjoy low fares and robust competition as some of our competitors have improved their networks through mergers," he said.