Boeing suffered a fresh setback on the opening of the Paris Airshow on Monday as its engine supplier announced a delay for the U.S. planemaker's all-new 777X jet while Airbus launched a rival plane aimed at the middle of the market.

GE Aviation said it had found unexpected wear in a part for the GE9X engine it is making for the 777X, the world's largest twin-engined jet, forcing a delay of several months while it redesigns and tests the part.

The news is another headache for Boeing as it continues to grapple with the grounding of its top-selling 737 Max aircraft in March after two deadly crashes.