France's Palace of Versailles is evacuating its visitors for security reasons and will be closed on Tuesday, the Chateau de Versailles said on social network X.
BFM TV, citing police sources, said a bomb squad was on its way to the site.
On October 14, one day after a teacher was killed in an attack, bomb alerts - which proved to be false - forced the evacuation of the Louvre museum, the Palace of Versailles and Paris' Gare de Lyon train station.