The court ruled Wednesday three teenagers and adult could be held for up to another 30 days. Three other teenagers charged were ordered held without bond for another 30 days last week, DutchNews.nl reported Thursday.
The seven, who have been in jail since December, are suspected in the death last year of soccer linesman Richard Nieuwenhuisen, who died after being kicked by fans of the Amsterdam football club Nieuw Sloten after a match against Almere side Buitenboys.
Judges rejected a request by lawyers for the teens, who are between 15 and 17, to release them so they could go to school.
The court said the investigation was still under way and involved very serious charges.
A preliminary hearing for the six teens and a 50-year-old man is scheduled for March 11.
In the Netherlands, juvenile offenders can be kept in jail without trial for 108 days.