U.S. airlines are postponing or reducing services to China as air travel slumps due to the global economic slowdown, state media reported.

Of the six non-stop China-U.S. services approved in 2007, only Delta Air Lines' Atlanta-Shanghai route and Continental Airlines' Newark-Shanghai route are in operation, the China Daily said.

"All U.S. carriers serving China have experienced much less favourable market conditions than were generally expected," said Delta in its request to cut the number of weekly flights between Atlanta and Shanghai, according to the report.

Northwest Airlines has delayed its Detroit-Shanghai service, while American Airlines has put off its Chicago-Beijing service until next year, it said.

United Airlines has also postponed the operation of its flight between San Francisco and the southern city of Guangzhou, it added.

The number of U.S. visitors to China fell by more than 15 percent during the first quarter of 2009 from the same period last year, while business-related travel plunged by more than a third, the report said, citing official figures.