Agence France-Presse quoted the university’s Valerie Angenot as saying she conducted an analysis based on the study of symbols.
It revealed that the sisters seized power until their baby brother Tutankhamun, aged 4 or 5 at the time, was old enough to take over.
King Tut, the boy monarch who ruled ancient Egypt, got the job only after two of his sisters jointly held the throne, according to a professor at the University of Quebec at Montreal.
Egyptologists have known for years that a queen ruled before Tutankhamun.