WASHINGTON, US - US airlines say they cannot afford to fly new routes or maintain all flights to China and other countries that restrict access, but they still want to keep their rights to serve those destinations.

'All US airlines are being forced to re-evaluate the flights they offer to avert financial catastrophe,' the carriers wrote in a joint application to defer service.

'In the present emergency circumstances, the resources of the carriers and the (government) should be focused on preserving the air transportation system and the viability of United States carriers,' they said.

American Airlines, a unit of AMR Corp ; Delta Air Lines Inc ; United Airlines, a unit of UAL Corp ; US Airways Group Inc ; Continental Airlines Inc ; and Northwest Airlines Co expect a decision soon from the Transportation Department.

They suggest others could fly the unused routes temporarily, but insiders say that would not happen.

The government granted similar waivers twice this decade.The first, only for four months, followed the 2001 hijack attacks on New York's World Trade Center and the Pentagon that accelerated the industry's worst-ever downturn. The second, for one year, occurred at the start of the Iraq war. The latest request, if granted, would represent one of the only government steps to assist airlines during the current downturn, which some analysts predict could be worse than the last one from 2002-06 when four big airlines went bankrupt. Airlines did not specify where they want to halt or slow service but some have said individually that China routes are too costly. Waivers would be required to defer or suspend some or all service to China, Brazil, Mexico, Japan, and several other countries where access must be negotiated by governments. -- Reuters