Three major U.S. airlines on Monday asked federal officials for a hearing on a proposed alliance between American Airlines and British Airways, saying they believe it would stifle competition.

In a joint filing with the Department of Transportation, Northwest Airlines, Delta Air Lines and Continental Airlines requested a hearing before an administrative law judge.

American Airlines, a unit of AMR Corp., and British Airways have applied to U.S. and European regulators for antitrust clearance so they can more closely share operations and revenues on routes between the U.S. and Britain.

But rival airlines have criticized the proposed pact and called for more access to London's Heathrow Airport to ensure competition.

Delta, Northwest and Continental said a hearing is essential to hammer out issues such as the landing slots available to rival carriers, frequency of service and how the alliance would affect fare prices.

"The stakes are too high for the department to complete the decision-making process behind closed doors without the benefit of a public hearing," said Scott Yohe, Delta's senior vice president for government affairs in a statement.

Yohe said US officials had agreed to a public hearing last time British Airways and American Airlines applied for anti-trust immunity.

The three airlines have asked the two leading carriers to give up at least 420 slots a week at Heathrow, one of Europe's most important hubs, to allow rivals fair access.

British and U.S. officials are currently examining a possible "open skies" agreement that could liberalize air traffic routes between the two nations. Competition at Heathrow has proven a sticking point during earlier talks.

In 1998, U.S. transportation officials scuttled a hearing about the previous application for antitrust immunity from American Airlines and British Airways to show displeasure at what they saw as stalling by their British counterparts.

Airlines are increasingly looking to international alliances as other nations open up air traffic and they struggle with huge losses from the travel slump after the Sept. 11 attacks.

The U.S. and France recently signed an agreement on their air traffic that Delta hopes will bolster its SkyTeam alliance with Air France and other carriers.