Delta Air Lines Inc.'s chief executive said Friday that the carrier will fight antitrust immunity for American Airlines Inc.'s proposed hookup with British Airways PLC and Iberia unless other airlines get more landing rights at London's busy Heathrow Airport.

In an employee hotline message, CEO Richard Anderson said Delta supports the joint venture "in principle," but "AA and BA need to give up enough slots and gates so that everybody has unfettered access to Heathrow."

On Aug. 15, American, British Airways and Iberia asked the U.S. Department of Transportation for antitrust immunity so they can cooperate on trans-Atlantic flights, including the right to jointly set fares and schedules and share revenue.

In their filing, the three airlines argued that the open-skies treaty signed last October between the United States and European Union was sufficient to allow other carriers access to London.

An American spokesman repeated that theme Friday when asked about Mr. Anderson's statements.

"We do not believe surrendering slots is necessary given the number of new entrants with service to Heathrow, which clearly demonstrates that slots are available through the open market and intra-alliance transfers," American spokesman Andy Backover said.

Mr. Anderson said Delta needs enough Heathrow takeoff and landing slots to operate five round trips a day from New York's Kennedy International Airport, three or four from Atlanta and two or three from Detroit.

"So you get the picture," Mr. Anderson said. "We've got to have open and free access."

Delta, which has antitrust immunity for its trans-Atlantic operations with the SkyTeam alliance, currently has two Heathrow daily round trips from New York and one from its Atlanta hub. It plans to merge with Northwest Airlines Inc., which operates a Heathrow daily round trip from Detroit, Minneapolis-St. Paul and Seattle-Tacoma.

Before the open-skies treaty went into effect in late March, only British Airways, Virgin Atlantic Airways Ltd., American and United Airlines Inc. had the legal authority to fly into Heathrow from U.S. cities.

The new air services deal allows any U.S. or European Union carrier to fly between any European Union and U.S. city, and Delta, Northwest, Continental Airlines Inc. and US Airways Inc. quickly began service to Heathrow.

But airlines are being forced to pay tens of millions of dollars to buy Heathrow landing rights from other carriers, and they'd rather get them for free from British Airways and American.