Boeing Co said on Tuesday that its next-generation 737 MAX jet will beat its previous fuel-efficiency target, delivering a 14 percent improvement, instead of the 13 percent gain promised earlier this year.

The 1 percentage point increase follows firm design configuration of the jet and completion of engineering reviews that confirmed the improvement over existing single-aisle jets, Boeing said on a conference call with reporters.

First delivery of the jet in the third quarter of 2017 is "on track," Boeing said.

The 737 MAX competes with the Airbus SA A320neo family of planes. Both are derivatives of current best-selling single-aisle aircraft with updated engines that are the main source of the fuel consumption savings.

(Reporting by Alwyn Scott; Editing by Maureen Bavdek)