Senior officials at French first division club Marseille including current President Vincent Labrune have been questioned over alleged illegal commissions for several high profile transfers.
Former Presidents Jean-Claude Dassier and Pape Diouf were also taken into custody by French police.
The investigation centres on whether the club officials took under-the-table commissions when conducting transfers notably of France international striker Andre-Pierre Gignac in 2010.
The transfers of Souleymane Diawara in 2009 and Didier Drogba in 2003 are also being reviewed for any suspicious activity.