The group that organized a solidarity march in response to recent terrorist attacks in Brussels called off the event in the Belgian capital, heeding a request by government officials.
"The security of citizens is the absolute priority," organizers of the March Against Fear said in a Saturday statement.
"Consequently, we completely join the authorities in their proposal to postpone to an ulterior date. We thus ask citizens not to come this Sunday to Brussels," the emailed statement added.
Before the announcement, nearly 6,000 people had confirmed that they would attend the event on Facebook. The organizers did not give a new date for the event.
The cancellation came swiftly after Belgian politicians advised people against participating in the march.
Belgian Interior Minister Jan Jambon and Brussels Mayor Yvan Mayeur asked people not to take part in the Sunday event, pointing to limited "police capacity" and the need to prioritize the investigation into the bombings, according to Belga news agency.
"We of course share the emotion of the population," the officials said. "But we would like for the marches to be delayed by a few weeks."
The event was set to start at 2 pm local time (1500 GMT) on Sunday at the Place de la Bourse, where locals have created a memorial with flowers and candles since Tuesday's attacks.
The city of Brussels had asked for the event to be postponed on Twitter.
Investigators were meanwhile trying to piece together who orchestrated Tuesday's attacks on the airport and a Brussels subway station that left at least 31 people dead, including the three perpetrators, and some 340 injured.
The Brussels crisis centre reported that 24 of the 28 victims have been identified so far. Among those injured, 101 remain in hospital, 62 of whom are in intensive care.
Earlier Saturday, federal prosecutors said a man detained earlier this week has been charged with terrorist murder in connection with the attacks. Media reports claimed he may have fled during the bombings at the Belgian capital's airport.
The Belgian federal prosecutor's office identified the charged suspect only as Faycal C, but local media reported his full name as Faycal Cheffou. He was taken into custody on Thursday evening.
Faycal C has been placed under arrest and charged with terrorist murder, attempted terrorist murder and participation in the activities of a terrorist group, the prosecutors said. His home has been searched, but no weapons or explosives were found.
A taxi driver who drove the attackers to the Brussels airport on Tuesday morning picked him out of a photo array, the newspaper Le Soir and the state broadcaster RTBF reported.
Prosecutors, waiting for the results of DNA analyses, had not yet confirmed Faycal C as the suspected third airport bomber, RTBF added.
The yet-unidentified fugitive suspect had been caught on video surveillance with the two suicide bombers who died in the airport attack. A picture released by the police shows a man wearing a white jacket and black hat pushing an airport trolley with a black duffel bag on it.
Prosecutors say the man brought a bag to the airport containing "the most significant" explosive charge prepared for the attacks, but then abandoned it there and left. The device only went off after the attacks, once a bomb squad was on the scene.
The airport said it will not resume passenger flights before Tuesday, adding that it is working to implement new security measures imposed by the Belgian government.
A provisional analysis by a team of engineers and other experts has found no stability issues with the main airport terminal or a connector building, the airport said in a statement Saturday, adding that authorities would next explore the possibility of installing temporary check-in desks.