"FC Bayern believe that the club has a responsibility to act as a role model," the Bundesliga team writes on its website.
Boateng was also involved in a minor traffic accident during his secret journey.
- I realize it was really a mistake not to tell the club that I was traveling, but I was only thinking about my son, Boateng tells Bild newspaper.
- He was not feeling well and if a son needs his father it is clear that I go to him, no matter when and how, Boateng continues.
It's unclear how sick Boateng's son is. The club has not disclosed the amount of the fine.