Delta Air Lines raised fares Friday on most U.S. round trips by $10, citing higher costs. Other airlines didn't immediately join in the move.
Delta's increase follows a 10 percent rise in the price of jet fuel for immediate delivery in New York harbor in the last month. Southwest Airlines raised round-trip fares as much as $20 on Aug. 31, triggering higher charges by seven other carriers including Delta.
"Fare increases reflect increased costs and fuel plays a big role in our business," said Betsy Talton, a spokeswoman for Delta.
Fuel and labor are the top two expenses for airlines. Each $1 change in the price of a barrel of oil takes $500 million off airlines' profits, according to Merrill Lynch.
American Airlines, United, Northwest and US Airways said they are studying the Delta increase. Continental and Southwest didn't increase fares, spokeswomen said, and JetBlue has no plans to do so, spokeswoman Alison Eshelman said.