United Continental Holdings Inc. is revamping some of its regional jets to add more first-class seats and amenities as part of a wider push to attract more business travelers.

The airline's remodeled short-haul aircraft, dubbed the CRJ550, will be an adaptation of a plane made by Bombardier Inc. that typically flies with 70 seats. That's 20 more than in United's new configuration, which adds more luxury seats while reducing economy berths. United plans to fly the jets by year-end in Chicago, followed by flights from Newark, N.J.

"We felt we were in a competitive disadvantage in certain markets," Chief Commercial Officer Andrew Nocella told reporters. "The CRJ550 is one of many things we're doing as a company to close that gap."

The upgraded regional offering is part of a broader fleet renewal at United as it races with Delta Air Lines and American Airlines to segment aircraft cabins for a full spectrum of customers, from lucrative business travelers to leisure passengers in the lowest-priced basic economy. United is adding more than 1,600 premium seats to almost 250 aircraft across the fleet, not just small jets.