The discovery was made by Scan Pyramids, a research project involving universities and advanced scientific instruments. Using a combination of thermography, 3D simulation and radiography imaging, the team discovered anomalies in the structure indicating the presence of holes beneath the rock.
One was discovered at the north-eastern edge of the pyramid and another on the northern face, where a 2015 study indicated one may exist, according to the research’s findings.
"The precise shape, size, and exact position of this void is now under further investigation,” the team said. “It should be done with the help of 12 new muon emulsion plates that are installed in the descending corridor, and will be collected by the end of October 2016."
Thought to have been constructed for the Pharaoh Khufu in 2560 BC, the Great Pyramid is the largest of the three Giza pyramids, standing at 146 meters (480ft) tall. For nearly 4,000 years it held the record for the tallest man-made structure in the world.
The technique used in the discovery involved muography, a process involving elementary particles weighing 200 times more than electrons passing through a structure to assist in the construction of an image. The discovery was the first time muography was used in collaboration with thermography and 3D simulation at the Giza site.
Until the anomalies can be seen and confirmed to be chambers, the research can be only theorised. Some scientists have cast doubt over the discovery, including Egypt's antiquities minister, Zahi Hawass, who believed the anomalies were the result of construction methods.
"These people are scientists and do not have an archaeological background,” Hawass told Seeker. “The core of the pyramid was built using long stones and small stones. If you know that, you'll find anomalies everywhere."
Scientists overseeing the research are recommending the project be extended by a year, in the hope of collecting more convincing data.
The Great Pyramid continues to surprise archaeologists thousands of years after its construction. In July, a defence “machine” was found in the pyramid, protecting the royal tombs from theft.