"This is better than the other theories, because it is the only theory that works," Houdin said after unveiling his hypothesis in a lavish ceremony using 3-D computer simulation. Houdin, 56, also brushed aside concerns about the popular curse which is supposed to punish those who penetrate the secrets of the pyramids, dating back to the opening of the Tutankhamen tomb.

"Why should I be worried? I'm just explaining that the people of the time were architects of genius and that Khufu was a genius to order the pyramid's construction. What could happen to me, except that Khufu would thank me?" Houdin teamed up with a French company that builds 3-D models for auto and aircraft design, Dassault Systemes, which put 14 engineers for two years on the project, to prove his theory. An international team is being assembled to probe the pyramid using radars and heat detecting cameras supplied by a French defence firm, as long as Egyptian authorities agree.

"This goes against both main existing theories," Egyptologist and senior research fellow at Long Island University, Bob Brier, said at the unveiling. "I've been teaching them myself for 20 years but deep down I know they're wrong. Houdin's vision is credible, but right now this is just a theory. Everybody thinks it has got to be taken seriously."

Egypt's Supreme Council of Antiquities was not immediately available for comment. Dassault said Brier and other Egyptologists attending the ceremony were supporters of Houdin's theory but had no financial links to him or the firm. Houdin began working full-time on the riddle eight years ago after a flash of intuition passed to him by his engineer father, and five years before actually visiting the site.

He found that a frontal, 1.5 kilometre-long ramp would have used up as much stone as the pyramid, while being too steep near the top. He believes an external ramp was used only to supply the base. An external corkscrew ramp would have blocked the sight lines needed to build an accurate pyramid and would have been difficult to fix to the surface, while leaving little room to work.

"What characterised the Egyptians was their sense of perfection and economy," Houdin said. Houdin also claimed to have shed light on a second enigma surrounding the purpose of a "grand gallery" inside the pyramid. He believes its tall, narrow shape suggests it accommodated a giant counterweight to help haul five 60-tonne granite beams to their position above the King's Chamber. He thinks that no more than 4000 people could have built the pyramid using these techniques rather than the 100,000 or so assigned by past historians.