A man puts down flowers at the condolence book for the linesman Richard Nieuwenhuizen on Saturday.
Ilvy Njiokiktjien/EPA

Dutch police have arrested four more suspects in their investigation into the attack on a volunteer linesman who died a day after players on a youth team assaulted him following a match.

The arrests on Tuesday bring to eight the number of suspects in custody in the case - seven of them teenagers.

Police say in a statement they have arrested three teenagers and a 50-year-old man, the first adult to be detained in the case, all from Amsterdam.

Linesman Richard Nieuwenhuizen's death just over a week ago sparked national soul-searching about the rising tide of violence on and around Dutch sports and how to rein it in.

Some 12,000 people attended a silent march Sunday to commemorate Nieuwenhuizen.

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