DALLAS — A government analyst says the merger of American Airlines and US Airways would reduce competition on more than 1,600 routes traveled by more than 53 million passengers.

A researcher for the Government Accountability Office said Wednesday that the loss of competition would be greater than occurred in the 2010 merger of United and Continental airlines.

American and US Airways executives have defended their combination, noting that they overlap on only 12 nonstop routes. But the GAO also considers connecting routes — those with at least one stop.

GAO researcher Gerald Dillingham says that competition would decline with the American-US Airways merger because there would be one less airline flying those connecting routes.

The Department of Justice is still studying the merger.