American Airlines Inc. warned Monday that efforts by the U.S. Justice Department to sway policy on industry alliances could threaten a landmark liberalization pact with the European Union.

The carrier fired the first industry salvo following the department's recent negative signals about a proposed pact involving Continental Airlines Inc. (CAL) and nine members of the Star airline alliance.

DOJ's comments on the Star request - which have already received tentative approval from the transportation department - threaten to complicate the separate application for antitrust immunity by members of the rival Oneworld alliance, led by British Airways PLC (BAY.LN) and American, a unit of AMR Corp. (AMR).

DOT has final say on the antitrust applications, but American said it had "serious concerns" about DOJ's "request" that different standards be applied to the applications now under review.

American, in its response to DOJ, said that failure to apply "consistent" standards could hit the existing open skies pact with the EU "in jeopardy," as well as a planned extension.

"While DOJ's comments appear to claim that all alliances are equal in their ability to compete for transatlantic traffic, the reality is that some are now more equal than others," said the airline in its filing.

-By Doug Cameron, Dow Jones Newswires; 312-750-4135; doug.cameron@dowjones.com