The postponement of the Easter Sunday rally underscored the tension in Belgium as police track members of an Islamic State group cell linked to both Tuesday's Brussels attacks that killed 31 as well as the Paris assaults in November.
The airport suspect officially identified as Faycal C, and named by sources close to the inquiry as Faycal Cheffou, was arrested on Thursday night as investigators believe he could be the third man pictured in airport surveillance footage alongside two suicide bombers.
In the grieving Belgian capital, a defiant "March Against Fear" had been planned for today from the central Place de La Bourse, which has become a shrine to the victims, but was called off after authorities said the mass gathering could draw much-needed resources away from the investigation.
"Let us allow the security services to do their work and that the march, which we too want to take part in, be delayed for several weeks," Brussels mayor Yvan Mayeur said.
More From This Section
Brussels airport meanwhile said an examination of the main building housing the departure hall wrecked by two suicide bombers showed the structure is stable and authorities will now see if temporary check-in desks can be installed.
In a separate statement earlier the airport said it did not expect to be able to reopen before Tuesday, with a partial resumption of passenger services, as it repaired the damage and put in place new security measures.
Many believe it failed to do enough to stop young Belgian fighters going to Syria, and two senior ministers have offered to resign after it emerged airport bomber Ibrahim El Bakraoui had been deported from Turkey as a "terrorist fighter".
"It is an endless nightmare for a country turned upside down," said Le Soir daily in a front-page editorial.
Heavily armed soldiers and police patrolled Brussels and the airport yesterday, as the city that is home to the EU and NATO headquarters remained on high alert.
Le Soir said on its website that the suspect had been identified by a taxi driver who drove the three bombers to the airport on Tuesday.