Giorgos Spanos, the president of the ETEKA fuel company, and four other suspects in a fuel smuggling racket are due to be taken to Korydallos prison on Monday.
A magistrate ruled on Saturday that the five should be remanded in pre-trial custody after being accused of adulterating diesel with bunker fuel and cheating the state out of millions in tax revenues.
Another six suspects were released from custody on Saturday after being asked to post bail of 3,000 to 7,000 euros. A female suspect was asked to post bail of 20,000 euros.
A total of 25 people are facing charges in the case. Fifteen of them have been arrested.