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A pair of French Egyptologists who suspect they have found a previously unknown chamber in the Great Pyramid (search) urged Egypt's antiquities chief to reconsider letting them test their theory by drilling new holes in the 4,600-year-old structure.

Jean Yves Verd'hurt and fellow Frenchman Gilles Dormion (search), who has studied pyramid construction for more than 20 years, are expected to raise their views during the ninth International Congress of Egyptologists in Grenoble, France, which starts Monday. They also published a book about their theory this week.

Standing in their way is Zahi Hawass (search), the director of Egypt's Supreme Council of Antiquities, who heatedly rejected the theories during a Cairo press conference this week.

"There are 300 theories concerning hidden rooms and other things inside the pyramid, but if I let them all test their theories they will do untold damage to the pyramid, which was built with the blood of Egyptians," said Hawass. "I will not let Egyptian blood be damaged by amateurs."

He said earlier requests from the same pair were turned down in 1999 and 2003.

In their book, "The Room of Cheops," Dormion and Verd'hurt write that 1988 study of an area below the queen's burial chamber in the pyramid found what appeared to be an 11 1/2-foot "structure," according to the French magazine Science and Future.

"The study of this part of the pyramid was always neglected because there had been a grill to block access," they wrote. "While we were working on ventilation in 1988, we were able to penetrate into the depths and study briefly but not enough to state anything essential."

Verd'hurt laughed off Hawass' "amateur" tag, citing previous close relationships with Egyptian antiquities officials and work that he and Dormion had conducted in 1998 on the Meidum pyramid south of Cairo, which dates back more than 4,500 years to the 4th pharaonic dynasty.

The work at Medium, according to Verd'hurt, led to the discovery of two rooms and two passages that had been previously "undisturbed and unknown." They want to do similar work at the Great Pyramid, built by Khufu, a ruler also known as Cheops.

"To be sure of this process, we wanted to verify the result of our architectural works using a radar that confirmed the location of a passage and a system of closures. So I think that now we should at least take these results into account in order to go further in our work."

Verd'hurt said Egyptian opposition to his theory is a "shame." They are expected to raise the issue again with Hawass in Grenoble, but the Egyptian antiquities official said he will not speak to them.

Verd'hurt said he was disappointed by Hawass' refusal.

"It's true that Cheops arouses and attracts passions but, with regard to history, it's really too bad," he said. "I think it's too bad that he doesn't sit down with us to let us explain ourselves."