Two U.S. airlines that won federal approval to begin routes to China just months ago are postponing the launch of the new services because of high fuel costs.

United Airlines has sought and US Airways plans to ask for one-year delay in launching the new routes, representatives from the carriers said on May 22. United won final approval and US Airways received the tentative go-ahead to launch the routes from the U.S. Department of Transportation in September.

The routes in question affect planned United service between San Francisco to Guangzhou, and US Airways flights between Philadelphia and Beijing.

Access to routes between the United States and China is highly competitive because air service between the two countries is restricted by bilateral agreements. A July agreement between the two countries was intended to double the number of daily flights allowed between the two nations during the next five years.

United's request for a delay was approved on April 25, while the request from US Airways has not yet been received, the Transportation Department spokesman Bill Mosley said.

United, a division of UAL Corp., was scheduled to start its new flights in early June, but now plans to postpone the launch until June 2009. Spokeswoman Robin Urbanski said the Chicago-based carrier is scaling back plans for one new international route, San Francisco to Guangzhou, where there aren't "strong enough economics" to offset higher fuel costs.

US Airways has begun sending letters to members of Congress and its employees saying it would seek to delay the launch of the new Philadelphia-Beijing route, noting that the cost for fuel would be more than US$90 million a year - US$40 million more than the original estimate.