The club made this known in a statement on their official website on Wednesday.
The club claimed he didn’t get along with management and had strained relations with players and staff.
The statement on their site read:
“The club management makes this decision as a result of the repeatedly culpable actions for a longer period by the trainer towards several persons in the organization.”
“Several attempts by the club to change his behavior remained unfortunately without result, resulting in an unworkable situation as a result.”
“’The board of Fortuna Sittard emphasizes that the decision to sack Sunday Oliseh is not motivated by current results.”
“The coach has a bad working relationship with players and staff.”
“Fortuna Sittard regrets the decision, but the interest of the club is above anything else”
Oliseh led Fortuna Sittard from the brink of relegation last season to the play-offs for top flight promotion this term.