WASHINGTON - U.S. commercial airlines and military aircraft would make a strong long-term market for synthetic alternatives to jet fuel, Glenn Tilton, the chief executive officer of United Airlines parent UAL Corp said on Wednesday.

Speaking at an energy conference, Tilton said commercial airlines remain financially fragile and do not have the cash to fund development of synthetic fuels.

Large-scale investment would be up to the government and other private industries, Tilton said. We're willing to step up and be the buyers, he said. (Reporting by John Crawley, editing by Gerald E. McCormick)