DALLAS - Southwest Airlines Co., which has bashed competitors for charging fees, said Friday it will add new fees for passengers who bring small pets onboard and for unaccompanied minors.

It will also raise the charge for checking a third piece of luggage or an overweight bag.

Other airlines have raised hundreds of millions of dollars since last year with new fees that include charges for checking one or two pieces of luggage and talking to reservations agents on the phone.

Southwest fired back by spending heavily on television commercials that blasted other airlines for charging "hidden fees." Southwest officials said they were winning customers turned off by the new bag fees.

On Friday, Southwest officials defended their own new fees, which Chief Executive Gary Kelly called "just the starting point" for more changes later this year.

"It is always our goal to be upfront with our customers and to set the right customer expectations," Kelly said. "Our changes today associate a charge for items that are truly an extra service."

Southwest has lost money the last three quarters, and it has joined all other airlines in searching for new revenue, a job made more difficult by a downturn in travel during the recession.

Southwest already charges for checking three or more pieces of luggage and for cocktails, and it is testing onboard Internet access for a fee. Kelly hinted last month that new fees were coming, while insisting they wouldn't be "hidden," by which he seemed to mean fees on first and second checked bags.

"It's disingenuous on our part to say that there are no, quote, fees," Kelly said last month. "We just try to be as honest and straightforward and have the right expectation with our customers on fees as we can."

Kelly said hidden fees are ones "that people don't think are right."

Starting with flights on June 17, Southwest will let small dogs and cats onboard — now only service animals are allowed — for $75 each way.

The Dallas-based discount airline will also begin charging $25 each way for unaccompanied children ages 5 through 11. That fee will apply to tickets bought after May 31 for travel June 17 or later.

And the fee for a third checked bag or a bag over 50 pounds but less than 71 pounds will rise to $50 from $25. Like JetBlue, Southwest still doesn't charge for the first two checked bags.

Veteran travel industry expert Terry Trippler said the new fees probably won't upset too many Southwest travelers.

"The fees for pets is something all airlines have — in fact, some are close to $150 one way, so at $75 Southwest is pretty low," Trippler said. Likewise, he said many airlines charge more for unaccompanied minors.

Trippler said bump in third-bag fee might cause some groaning, but Southwest said only 1 percent of travelers check a third bag.