More radar scans will be done at the end of the month in order to determine the size of the chambers
Egypt's Ministry of Antiquities has confirmed that scans done on King Tutankhamun's tomb last November show there are two hidden spaces or chambers behind it.
The ministry said the scans also showed that there is organic and metallic matter in the chambers, suggesting it could be another burial site.
Egypt’s Minister of Antiquities, Mamdouh el-Damaty, told reporters in Cairo this could be "the discovery of the century".
"It means a rediscovery of Tutankhamun. It is very important for Egyptian history and for all of the world," he added.
British Egyptologist Nicolas Reeves has argued that Queen Nefertiti's burial chamber is in the room beyond her stepson King Tut’s tomb.
The idea is that the sudden and early death of the King caught everyone by surprise and as they didn’t have time to build a tomb, they buried him in Nefertiti’s.
Mr Reeves points to the fact the tomb looks similar to others that were built for women, contained artefacts belonging to a female and is too small for a king.
But other Egyptologists say that, although there may be chambers, there are unlikely to be "new" tombs, still less that of the notorious Nefertiti.
Dr Aidan Dodson, an Egyptologist and Senior Research Fellow at the University of Bristol, told Sky News: "We need to be careful about separating reality from speculation.
"There are interesting marks on that wall in King Tut’s tomb - fact.
"That they look possibly like the outlines of doorways I think we all agree with. But after that it goes into a range of possibilities."
Dr Dodson and others have questioned why Egypt has been so slow to reveal the results of the scan.
By drilling a small hole into the wall and feeding in a fibre optic camera, they argue, we would be able to determine exactly what are in those chambers.
But Egyptian authorities say they don’t want to risk any damage to the tomb or priceless paintings on the wall until they are 1005 sure there is something in there worth exploring.
King Tut’s tomb was found in 1922 in good shape and considered to be the biggest antiquities find of the century. Now, decades later, an even bigger discovery may be revealed.
Queen Nefertiti, who ruled alongside her Pharaoh husband in mid-1300s BC, was one of ancient Egypt’s most important and influential figures and has become a symbol of Egyptian culture and history.
The next step will be on 31 March when more radar scans will be done in order to determine the size of the chambers and thickness of the walls.
The results of that scan could be announced as early as 1 April in Luxor at the Valley of the Kings.
Egyptologists say even if nobody is buried in those chambers it is still of major archaeological value that they are there at all.