Continental Airlines yesterday agreed to pay a $250,000 civil penalty in connection with consumer complaints about overbooking, ticket refunds and baggage claims.

The penalty is part of a consent agreement with the Department of Transportation, which has come under intense pressure from Congress and consumer groups to act on the rising number of complaints about airline service.

Such complaints nearly tripled in May, rising to 2,816 from the same month last year. Continental has been the leader in that gripe derby, based on the number of complaints per 100,000 passengers served by 21 airlines.

Continental, owned by Houston-based Texas Air Corp., racked up 793 complaints -- 21.39 per 100,000 passengers -- last month, according to DOT figures. The complaints largely concerned cancelled and delayed flights and baggage problems.

Eastern Air Lines, recently acquired by Continental, was second, with 10.11 complaints per 100,000 passengers.

As part of its consent agreement, Continental said it will offer confirmed reservations to passengers bumped from overbooked flights. In the past, the company gave bumped passengers standby vouchers.

Current holders of standby vouchers are covered under the change.

The airline also agreed that it will make more timely refunds on tickets purchased by credit cards, and that passengers will be fully informed if a commuter carrier, rather than Continental, will provide service on a booked flight.

There has been confusion among customers on Continental and other carriers about interpreting codes on tickets that signal the type of aircraft that will be used on a flight.

Continental President Thomas G. Plaskett yesterday apologized for his airline's performance, saying that the company's management is "truly sorry for the customer inconvenience" that resulted from scheduling miscues and baggage mishaps.

Plaskett said most of the problems were rooted in Continental's merger last February with People Express, which was financially crippled at the time of its acquisition.

Frontier Airlines also was brought into the Texas Air empire last year, making Texas Air the largest airline holding company in the United States. The net effect of Texas Air's buying spree has been an increase in revenue passenger miles last month to 3.1 billion, compared with 1.7 billion a year ago.

That incredible growth has generated problems.

Those and other unpleasant discoveries hampered Continental's efforts to offer quality service, the airline's officials say. "We believe that the vast majority of these problems are behind us," Plaskett said.

Overall, consumer advocates praised the Transportation Department's enforcement action.