Experts from Italy, Britain and Egypt were ready to begin a "decisive" search for possible hidden chambers in King Tutankhamen's tomb in the southern city of Luxor on Wednesday.
The scanning, using ground-penetrating radars, is aimed at verifying the presence of empty spaces or corridors hidden behind the walls of the pharaoh's burial chamber.
British Egyptologist Nicholas Reeves has previously said a detailed examination of photographs and scans of the tomb's northern wall suggested it concealed an opening into a further chamber.
Reeves proposed that the hidden chamber could contain the tomb of Queen Nefertiti, the wife of Tutankhamen's father, the pharaoh Akhenaten.
After almost a year of waiting, researchers at the Italian University of Turin finally obtained the green light from Egypt for conducting "decisive geo-radar measurements" from inside the tomb, they said.
The group, who also includes Egyptian and British experts, will conduct the search until February 6, the mission's lead investigator, Franco Porcelli said.
"The possible existence of hidden structures of relevance in the archaeological site adjacent to the tomb of Tutankhamun can be established with a 99-per-cent degree of confidence," the Turin researchers said.
Data obtained in May suggested the presence of cavities in the rock a few metres away from the tomb.
Tutankhamen's tomb, discovered in 1922, was a unique find among the pharaonic tombs in Luxor's Valley of the Kings due to the wealth of its contents.
Unlike most of the other tombs, it had not been systematically plundered in ancient times.