Little is known about the six new suspects, but their arrest only hours after a tenth terror suspect was charged with "terrorist murder," reveals the willingness of Belgian authorities to get to the bottom of the investigation into the Paris terror attacks.
Federal police have stepped up raids in and around the Belgian capital, after receiving warnings that a terror plot was being planned there on New Year's Eve.
The arrested men, whose names have not been made public, are due to go before a magistrate, who will decide whether to hold them for another month.
Belgian authorities say they have strong reason to believe they were preparing attacks directed at police, soldiers and popular attractions in the capital Brussels.
The terror threat was sufficiently high that officials were forced to scrap the New Year’s Eve fireworks display and related festivities in the city centre.
This, after two other suspects were also detained on suspicion they too were hatching a terror plot.
Computer equipment, mobile phones, and propaganda material from the Islamic State, were seized earlier this week when police raided their homes.
Then on Wednesday, police hit the troubled neighbourhood of Mollenbeck to arrest their tenth terror suspect, Ayoub B.
Belgium has been one of Europe’s leading recruiting grounds for foreign jihadi fighters, and was home to four of the attackers who killed 130 people in Paris in November, including suspected ringleader Abdelhamid Abaaoud and fugitive Salah Abdeslam.
Nine other people have been arrested in Belgium in investigations linked to the Paris attacks, which were claimed by Isis.
In France, authorities were also preparing for a possible worst-case scenario over the new year. About 60,000 police and troops are to be deployed throughout the country to oversee the end of year celebrations.