DALLAS – Continental Airlines will let passengers hold a reservation and lock in a quoted ticket price for up to a week – for fees that vary widely.

The service, called FareLock, gives travelers three days or a week to decide whether to buy a ticket and avoid a fare increase or the chance that a preferred flight or fare will sell out.

Continental said last week it will charge a fee of at least $5 to hold a reservation for three days and at least $9 to hold it for a week. The amount will vary depending on the length of the hold, the trip and how soon passengers plan to travel.

On round-trips in January between Houston and San Francisco, and between Newark, N.J., and London, the Continental website quoted fees of $19 each to hold reservations for seven days.

The fee was $44 to lock in a fare for three passengers traveling in January from San Francisco to Newark, but the service wasn’t offered on a journey from Los Angeles to Tokyo.

Continental didn’t say for which routes it would offer the service, except that the list includes both domestic and international flights.

Continental said it will still give customers 24 hours to change or cancel a reservation for a full refund. But it will continue to charge to change a ticket after that, without FareLock.

The new fee could reduce the amount airlines raise in change fees.

Airlines added an array of fees in 2008. The Department of Transportation said Monday that U.S. airlines raised more than $4.3 billion in the first nine months of this year with fees for checking bags and changing ticket reservations.

This month, US Airways President Scott Kirby said that fees will account for all of his company’s profit for 2010.

The most lucrative fees have been for checking baggage – $590.4 million in the third quarter – and for changing reservations.

Airlines have also tacked on fees for pillows and blankets, seats with more leg room, and buying tickets from a reservations agent instead of an airline website.

Travel experts said the latest fee from Continental might appeal to business and leisure travelers who aren’t positive about their plans – a business flier worried that a meeting might fall through, for example.

Anne Banas, executive editor of website SmarterTravel, said she might consider paying a $39 fee to hold a reservation for a January trip to India until she’s sure that she’ll get her visa on time.

Banas said bag fees hit a broad cross-section of travelers, but increasingly airlines are establishing fees “for things that are more optional,” such as the right to lock in a price.

“This one could be useful,” she said, but added that many travelers who know when and where they’re flying won’t need it.

Continental is owned by United Continental Holdings Inc.