The Airbus A400M will cost the seven countries buying the military transport an additional 7.4 billion euros for the 180 aircraft on order, Les Echos newspaper reported in a preview of the front page of its Tuesday edition.
This would be an increase of 40 percent, the paper said.
Airbus Military, which makes the plane, referred calls to parent company EADS, where no one was immediately reached for comment.
The 20 billion-euro ($30.07 billion) A400M programme is Europe's biggest ever defence contract, and the seven nations buying the plane include Belgium, Britain, France, Germany, Luxembourg, Spain and Turkey.
(Reporting by James Regan, editing by Leslie Gevirtz)