At a time when major airlines are cutting capacity, Southwest Airlines (NYSE:LUV) says it is adding more international routes through its subsidiary AirTran Airways.

The Dallas-based company will add new nonstop routes from Fort Lauderdale and Hollywood to San Juan, Puerto Rico, and new Denver and Houston nonstop routes.

The discount carrier is seeking government approval to add four new nonstop routes to Mexico starting next summer. Those would include a route from San Antonio, Texas to Mexico City and Cancun starting in May 2012, and Orange County, California to Cabo San Lucas and Mexico City starting in June.

AirTran, which currently offers international flights to destinations in the Caribbean such as Aruba, Bermuda and the Bahamas, has never previously serviced Orange County. Southwest acquired AirTran earlier this year to expand its reach in the U.S.

“We have been very encouraged by the success of AirTran's existing international service and we look forward to building upon that success," said Bob Jordan, Southwest Airlines chief commercial officer.

While the airline is adding new routes, the company has still suffered along with its peers under high fuel costs and lower demand that have squeezed operating margins. Last week, Southwest said AirTran would stop operating at U.S. airports in Knoxville, Tennessee; Miami International; Central Illinois Region Airport/Bloomington/Normal, Illinois; Charleston’s Yeager Airport in West Virginia; and Dulles International near Washington D.C.

Southwest’s operations at Dulles will continue unchanged, and the company said affected employees will have the opportunity to relocate.

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