WASHINGTON -- Leaders of some of the nation's largest airlines asked Congress for additional financial help Tuesday, saying fewer passengers and higher security costs since Sept. 11 are devastating the industry.

Little more than a year after the airlines received a $15 billion aid package from Congress, they asked the House aviation subcommittee to consider tax relief, reimbursement for security costs and an extension of the terrorism insurance policies issued by the government after the Sept. 11 attacks.

"Airlines are not asking Congress to assist with economic or competitive challenges, but we do request that the government relieve the industry of government-imposed security costs stemming from the nation's war on terrorism," said Leo Mullin, chief executive of Delta Air Lines.

Rep. John Mica, R-Fla., chairman of the aviation subcommittee, said the airlines wouldn't get a government bailout but could expect some assistance with security costs.

"They need our help," he said.

Donald Carty, chief executive of American Airlines, said half of the airline industry's expected $7 billion in losses this year could be attributed to security costs. He predicted layoffs, bankruptcies and route cuts if the government doesn't help out.

On Wall Street, persistent worries about the industry's finances caused the stock prices of American and Delta to tumble to levels not seen since the early 1980s. Shares of American, the nation's largest carrier, dropped 62 cents, or 15 percent, to $3.60; those of Delta, the third-largest airline, fell $1.24, or 11 percent, to $10.06.

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