A person close to the family told Reuters the 35-year-old had been arrested after flying a drone in the desert near the Turkmenistan-Iran border.
French officials and his family had sought until now to keep the information secret due to the current disputes in the region, fearing it could harm potential negotiations.
Iran’s judiciary was not available to comment.
France’s foreign ministry confirmed that a French citizen was being held in Iran, adding that it was monitoring the situation.
It said the French citizen benefited from consular protection and that embassy officials had been in regular contact with him.