NEW YORK - Turns out that new airline checked-bag fee wasn't the end of it.

Airlines ratcheted up the pressure on fliers ahead of the holiday weekend, significantly raising ticket prices to offset the runaway cost of fuel. The three biggest carriers boosted most domestic fares by up to $60 round trip, while budget airline AirTran Airways raised its leisure fares by $30 round trip.

UAL Corp.'s United Airlines led the round of increases late Thursday, lifting round trip ticket prices by $10 to $60, depending on how far passengers fly and the competition on the route. Travelers will pay the biggest increase on routes of 750 miles or more - less than the distance from New York to Chicago - that low-cost carriers such as Southwest Airlines Co. do not serve.

AMR Corp.'s American Airlines, the biggest U.S. carrier, and No. 3 Delta Air Lines Inc. matched the increase yesterday.

Separately, AirTran raised leisure ticket prices $30 and business-class fares $50 round trip.

The increases came just days after American said it would begin charging customers $15 to check a single piece of luggage. Representatives from a number of other carriers, including US Airways, many of which are already charging $25 for a second checked bag, said they were considering following suit. US Airways also said yesterday that, starting June 1, it would stop serving free snacks in coach on domestic flights.

Airlines are under pressure to boost revenue and cut costs as fuel prices have soared. As of Monday, spot prices for jet fuel in New York were up 43 percent from the start of the year, according to the Energy Information Administration.

Chicago-based United has been among the most aggressive carriers in pushing fares and fuel surcharges higher, and its increases are often matched by competitors. Airlines are prohibited from agreeing to simultaneously raise fares, but they can follow a rival's lead.

"Airlines have no choice but to pass on the cost of fuel to consumers and when passengers do begin to push back in significant numbers, the airlines have no choice but to slash capacity," Rick Seaney, chief executive of FareCompare.com, said via e-mail. He said this latest round would mark the 16th attempted airfare increase of the year. About 11 of those stuck to some degree.

In another sign of the pressure facing air carriers, Northwest Airlines Corp.'s cargo division said yesterday that it was raising its fuel surcharges on domestic and some international routes.

Midwest Airlines and Frontier Airlines, meanwhile, became the latest carriers to announce charges for second checked bags yesterday.