Yanbu serves as the kingdom's primary crude export terminal on the Red Sea and is connected to its oil-producing regions near the Gulf coast by the East-West pipeline, also known as Petroline.
The suspects were part of a group of 47 French nationals transferred last year from Syria to Iraq, where numerous suspected IS members were already being held.
TotalEnergies service stations are accused of distorting competition as they display France's lowest-priced fuel. Supermarkets that usually sell fuel as a loss leader to pull in customers are furious, along with independent service stations.