Tyson Fury and Wladimir Klitschko will weigh in behind closed doors on Friday on the advice of the police.
The heavyweights will come face to face for the final time before they touch gloves for their world title fight in Dusseldorf the following evening.
But the traditional stare down will be witnessed only by accredited media.
Fury’s trainer and uncle, Peter, tweeted: “I’ve been advised press conference and weigh-in are closed to public due to security here by police.
“If fans want pics or to see Tyson outside [then it’s] no issue for us. Unfortunately it’s out of our hands when it’s national security.
“Tyson says if the fans are there he’s happy to have it outside with the fans.”
Security in the German city has been tightened after the terrorist attacks in Paris earlier this month.
Klitschko’s manager, Bernd Boente, said: “After what happened in Paris, there has been a significant upgrade. It is common sense.
“It was the same last weekend for the Bundesliga for divisions one and two. We have special security measures in place, and we have had a close relationship with the security authorities in the build-up to this fight. We had a huge meeting of all parties last week, and we will be going over any new intelligence in another meeting this week.
“The security measures will make it extremely strict both inside and outside the arena. The police are taking their own measures, and there will be a huge presence both regular and under cover.”