Egyptian antiquities authorities on Thursday made public the discovery of a hidden chamber inside the 4,500 year old Pyramid of Khufu — formerly known as the Pyramid of Cheops — or the Great Pyramid of Giza.

The discovery, which was credited to scientists from the ScanPyramids project, was announced by archaeologist Zahi Hawass and Minister of Tourism Ahmed Eissa.

ScanPyramids, initiated in 2015, is an international project that uses various high-tech instruments employing non-invasive infrared thermography, ultrasound, 3D simulations and cosmic-ray radiography to study the structures.

Scientists say they used that technology to discover a sealed-off corridor above the main entrance to the pyramid. The corridor, which is not accessible from outside the structure, is nine meters (29.5 feet) long and two meters (6.5 feet) wide.

After the discovery was made, scientists fed a small diameter (6 millimeter: 1/4 inch) Japanese endoscope through a crack between stones to attain images of the space from inside.

Archaeologists say they do not know what purpose the corridor served.

Mostafa Waziri, head of Egypt's Supreme Council of Antiquities, suggested the corridor may have been designed to redistribute weight above the main entrance or around another as yet undiscovered chamber.

Christoph Grosse of the Technical University of Munich, a leading member of the ScanPyramids project, said he hopes to uncover still more hidden secrets. Speaking of the newly discovered corridor, he said, "There are two large limestones at the end of the chamber, and now the question is what's behind those stones and below the chamber?"

Major tourism magnet in cash-strapped country

Located just outside Cairo, the Pyramid of Khufu — named after a Fourth Dynasty pharaoh who reigned from 2509 to 2483 B.C. — is one of the three structures that make up the Giza pyramid complex.

The structure is the only of the Seven Wonders of the Ancient World to have survived to this day.

Originally built to a height of 146 meters, and now standing at 139 meters, the Pyramid of Khufu was the tallest manmade structure in the world until 1889, when the Eiffel Tower was completed.

The question of how exactly the pyramids were built has confounded experts for centuries.

The mystery surrounding them has also made them a main tourist attraction in Egypt, which depends heavily on the tourism sector for income.

The sector has suffered as a result of political turbulence since strongman President Hosni Mubarak was ousted in a 2011 uprising. Violence and the coronavirus pandemic have further crippled tourism in the cash-strapped nation.

js/ar (AP, Reuters)