The  CEO  of  a  credit  institution  must  be  of  Tunisian  nationality.  When the bylaws provide for separation of the functions of the board chairman and president, or those of the  chairs  of  the  management  board  and  the  oversight  body,  one  of  these  functions  must  be performed by a person of Tunisian nationality.
"Art. 27. - The CEO of a credit institution, governed by this law, must be of Tunisian nationality.
However, when the statutes of a credit institution provide for the dissociation between the function of chairman of the board of directors and that of managing director, or the dissociation between the function of the chairman of the management board and that of the chairman of the supervisory board, one of these functions must be performed by a person of Tunisian nationality. [...]" (Law on credit institutions (n° 2001-65 of 10 July 2001), as amended by Law n° 2006-19 of 02 May 2006, Article 27 [google translation])
Law on credit institutions (n° 2001-65 of 10 July 2001), as amended by Law n° 2006-19 of 02 May 2006, Article 27 
[<a href="https://www.pist.tn/record/111441?ln=fr">Law</a>]