Italian researchers who conducted extensive studies with ground-penetrating radar found the tomb does not contain any hidden, man-made blocking walls as was earlier suspected, a spokesman for Egypt's Supreme Council of Antiquities said.
King Tut's tomb secrets have disappeared.
Egypt's Antiquities Minister, Khaled al-Anani, said the authorities in the country accepted the results.
But in a news release issued on Sunday, the ministry said more detailed scans provided "conclusive evidence on the non-existence of hidden chambers adjacent to or inside Tutankhamun's tomb".
It has always been speculated that beyond King Tut's tomb were a number of hidden chambers, but without any real proof.
Results of a scan of the walls of the tomb found by the archaeologist Howard Carter in the Valley of the Kings in 1922 found no sign of the rooms.More news: DHS Ends Temporary Protected Status For Hondurans
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Reeves had theorized in 2015 that the tomb belonged to Nefertiti, the wife of Tutankhamun's father, King Akhenaten.
"Our work shows in a conclusive manner that there are no hidden chambers, no corridors adjacent to Tutankhamun's tomb", Dr Porcelli said. His suspicions were based on high-definition laser scans; other scans by Japanese and American scientists were inconclusive.
Tutankhamun, one of the last kings of Egypt's 18th dynasty, died at around the age of 19 under mysterious circumstances.
File photo - View of the Treasury chamber of Pharaoh Tutankhamun's tomb ahead of the opening of a major exhibition on the Ancient Egypt called "Tutankhamun, his Tomb and his Treasures" in Paris May 11, 2012.
The search for the hidden tomb began when English archaeologist Nicholas Reeves, examining detailed scans of the chamber, discovered what looked like faint traces, or "ghosts", of doors beneath the plaster.
The ministry had been gradually moving King Tut's belongings to a new museum outside Cairo near the Giza Pyramids to undergo restoration before they are put on display. Parts of the $795 million Grand Egyptian Museum - including exhibits focusing on Tutankhamun and his time - are due to open this year, with a grand opening planned in 2022.