The DFB has opened investigations against Fortuna Dusseldorf and Union Berlin after their fans had held up abusive banners against the governing body.
During Fortuna Dusseldorf's match against Borussia Monchengladbach in early September, Dusseldorf fans held up two abusive banners in response to the fact that some 20,000 fans were unable to witness the club's return to the Bundesliga after a 15-year absence.
The DFB had forced Dusseldorf to close parts of their stadium for their opening two home games in punishment for the pitch invasions that came shortly before the final whistle in the team's promotion play-off against Hertha Berlin at the end of last season.
Union Berlin supporters also held up a banner before their 2. Bundesliga match against Hertha Berlin. Last season, the DFB had brought an end to all talks with supporters over the use of flares at games, and every club in the top two tiers bar Union Berlin signed an agreement stipulating measures to stop fan violence. The agreement included a strict ban on the use of flares.
Union Berlin president Dirk Zingler had said on Friday last week that the club was working to prevent future protests. "We we will do everything in our power to identify the offenders," he said. "Anyone who brings damage to our club in this way will have to face the consequences."