Using high-tech scanning technologies, experts have detected anomalies in the ancient pyramids of Egypt. The Antiquities Ministry said on Monday that new thermal scanning of the pyramids identified anomalies in the 4,500 year old structures believed to be the burial grounds of royalties.

The project called Scan Pyramids, used a mix of technologies which include infrared thermography, 3-D construction and muon radiography to look inside pyramids.

Scientists have so far scanned parts of four pyramids, namely Khufu, known internationally as Cheops, and Khafre, or Chephren, at Giza, and the Bent pyramid and the Red pyramid at Dahshur.

Significant anomalies were particularly found among the stones of King Khufu's Great Pyramid in Giza, the largest of the three Giza pyramids. Giza's Great Pyramid was built by the son of Snefru, who founded the fourth dynasty.

Infrared thermal scans identified temperature discrepancies, which scientists said may reveal hidden gaps in stones or places where different types of materials were used.

Temperature differences between adjacent stones from limestone with varying qualities often range from 0.1 to 0.5 degrees but the research team detected a 6-degree difference at the ground level of the Khufu pyramid.

 "This anomaly is really quite impressive and it's just in front of us, at the ground level," said Paris-based Heritage Innovation Preservation Institute founder Mehdi Tayoubi. "This anomaly is impressive and obvious. We have several hypothesis but no conclusion for the moment."

The researchers carried out thermal measurements at different times of the day to observe the pyramids during their warm-up phase to cooling phase. If an object is constructed with blocks of the same material and has identical heat emissivity, there should be no significant temperature differences.

Cavities or the use of different materials, however, could be marked by temperature differences because some parts of the structure heat up or cool down at different rates.

Antiquities Minister Mamdouh Eldamaty said that they do not know yet what lies behind the blocks or what the anomalies could be but he is optimistic that this could lead to major discoveries. He said these anomalies could be fissures, passages or void spaces.

The researchers said that the anomalies will all be subjected to further analysis and hypotheses will be tested using models and thermal simulations.