They are suspected of insubordination against the police, passion of banned weapons, assault and criminal damage.
The Brussels-Capital-Elsene Local Police Service says that the 11 people detained are all dock workers, 10 of whom are Dutch-speaking.
A criminal investigation was already running against four of those detained. They were taken into to custody to the request of an Examining Magistrate. The 7 other have been summoned to appear in court next month.
Police already detained other suspects during operations carried out on 20 November and 10 December last year.