SkyWest Inc., the U.S. regional carrier with the world's largest fleet of Bombardier Inc.'s CRJ jets, agreed to buy 22 more of the planes in an order valued at $773 million.

The purchase includes 18 CRJ-700 NextGen and four CRJ-900 NextGen aircraft, the companies said in a statement Friday. St. George-based SkyWest also took options on another 22 of the planes that can be applied to either model.

SkyWest will use the aircraft on commuter flights it provides for UAL Corp.'s United Airlines and Delta Air Lines Inc.