The cancellation comes after authorities arrested two people on suspicion of being involved in a plot to attack "emblematic sites" in Belgium's capital during New Year's celebrations.
The country's federal prosecutor's office announced the arrests Tuesday.
The men are members of a Muslim biker gang called the Kamikaze Riders and are suspected to have discussed attacking Brussels' Grand Place square and other places where crowds gather as well as police and military facilities, a senior Belgian counterterrorism official told CNN on condition of anonymity.
The plot appears to have been inspired, but not directed, by the ISIS
terror group, the counterterrorism official said.
Because the investigation is in its early stages, a possible connection between suspects and ISIS cannot be excluded, André Vandoren, the head of Belgium's coordinating body for threat analysis, told CNN on Wednesday.
The arrests came as investigators conducted several searches in the Brussels area, as well as the surrounding province of Flemish Brabant and the eastern Belgian city of Liege, on Sunday and Monday, the prosecutor's office said.
Authorities were investigating an alleged plot that was to target several prominent sites in Brussels during "the end of the year/New Year's celebrations," according to the prosecutor's office, which released no further details about the plan.
The prosecutor's office said the arrests are not linked to November's deadly Paris terror attacks
, which authorities say involved a number of militants who had been living in Belgium.
Investigators seized computer equipment, military-type training outfits and ISIS propaganda material, the office said.
The names of the suspects were not released. But the counterterrorism official said they were based in the Brussels and Vilvoorde areas, had easy access to weapons and had been involved in robberies and other criminal activity.
Because of the pair's access to weapons, police felt they had to act quickly after the two allegedly discussed the terror plans, the counterterrorism official said.
One of the men was arrested on suspicion of playing a leading role in the threat of attacks, participating in the activities of a terrorist group as a leader and recruiting to commit terrorist offenses as author or co-author, the prosecutor's office said.
The other was being held on suspicion of playing a leading role in the threat of attacks and taking part in the activities of a terrorist group as an author or co-author, the office said.
The Kamikaze Riders gang in Belgium has been linked to terror investigations in the past, according to multiple Belgian media reports. A former leader of the group, Abdelouafi Elouassaki, was arrested in 2013 after one of his brothers, said to have traveled to wage jihad in Syria, allegedly called him from there to tell him about a plan to attack the main law courts in Brussels. Elouassaki was released without charge. At least one other member of the group has also been reportedly tied to pro-jihadi activity.
Morten Storm, a former Danish biker gang member who became a jihadi before becoming a double agent for the CIA for half a decade, told CNN that there was an increasing emergence of "gangster jihadism" in Europe. "Muslim gangsters and jihadis have one thing in common: They hate the system," Storm said. "A significant number of Muslims involved in criminality are becoming born again in the religion and are becoming radicalized in jail, but many keep their ties to their old circles when they get out," he said.
Paris attack: 25 messages exchanged
New details emerged Wednesday in the investigation into the November 13 Paris attacks.
A Samsung phone that was recovered outside the Bataclan concert hall -- where dozens of concertgoers were gunned down -- exchanged 25 messages before the attack with a phone that was in Belgium, the Belgian counterterrorism source and another source close to the investigation told CNN on condition of anonymity.
The messages started the day before the attacks, and the last one extracted from the Samsung -- sent on November 13 -- read "about to start," the sources said.
The sources didn't say who had the phone in Belgium, where several of the Paris attackers had lived. The phone in Belgium was deactivated right after the Samsung's final message was sent, the sources said.
Previously, Paris prosecutor Francois Molins told reporters that one of the attackers' cell phones was found in a trash bin outside the Bataclan, and that a message on the phone said, "On est parti, on commence," which translates to, "We've left, we're starting." But authorities at the time did not say the phone was communicating with a phone in Belgium.
The phone in Belgium was the only phone communicating with the Samsung on November 12 and 13, the two sources said.
The latest details about the messages were first reported by the French newspaper Le Monde.
The Samsung had downloaded a Telegram encryption application on the afternoon of the attack, the sources said. It wasn't immediately clear whether any of the 25 messages were handled by the application.
Earlier this month, officials briefed on the investigation told CNN that investigators believed some of the attackers used encrypted applications to hide plotting for the attacks
On the afternoon of the attacks, the Samsung phone was used to access floor plans of the Bataclan, as well as information about the American band that was playing at the venue that night, the Eagles of Death Metal, the sources said.
Also Wednesday, the two sources said the Paris attacks' ringleader, Abdelhamid Abaaoud, was in Paris communicating on a phone with someone using a separate phone in Belgium during the attacks. The sources did not say who was using the second Belgium phone.
French authorities have previously said Abaaoud was in Paris, at times near the Bataclan, during the attacks with a phone. The Paris prosecutor has said that Abaaoud's phone records show he was communicating November 13
with one of the three attackers who self-detonated outside the Stade de France north of Paris.
The November 13 terror attacks in the Paris area killed 130 people and wounded hundreds. The attackers, armed with assault rifles and explosives, attacked six locations across the city, including the Bataclan concert hall, a stadium, and restaurants and bars.
ISIS claimed responsibility for the attacks, and in response, French President Francois Hollande
declared that the country was at war with the terror group, which commands large stretches of territory in Syria and Iraq.
Abaaoud, a Belgian-Moroccan ISIS operative, was killed in a police raid on an apartment in the Paris suburb of Saint-Denis six days after the Paris attacks.