The corridor, which measures nine metres by two metres, is perched above the famous structure's main entrance and was detected using a scan, authorities said.

The function of the chamber is currently unknown, although such corridors often lead to further archaeological discoveries.

Egyptian archaeologist Zahi Hawass and the country's Minister for Tourism Ahmed Eissa announced the discovery at the pyramid's base.

The chamber was discovered by the Scan Pyramids project, an international program that uses scans to look at unexplored sections of the ancient structure.

The pyramid about 18km from Cairo's centre is also known as Khufu's Pyramid for its builder, a 4th Dynasty pharaoh who reigned from 2509 to 2483 BC.

The ancient structure is the last surviving wonder of the ancient world.

It has captivated visitors since it was built as a royal burial chamber 4500 years ago.

Experts are divided over how it and other pyramids were constructed, so even relatively minor discoveries generate great interest.

Egypt often publicly touts ancient discoveries to attract more tourists, a major source of foreign currency for the cash-strapped country.

The sector suffered a long downturn after the political turmoil and violence that followed a 2011 uprising.

Australian Associated Press