- The suspect was identified as Mohamed R of French nationality
- He was suspected to have been "under the influence of something"
- The driver sped off after Belgian soldiers tried to stop the car
"Different arms were found in the boot -- bladed weapons, a riot gun (rifle) and a container of liquid that is still unidentified," the federal prosecutor's office said in a statement.
"The suspect is Mohamed R., born on May 8, 1977, of French nationality and a resident of France," the statement said.
Belgian police arrested a man on Thursday after he tried to drive into a crowd at high-speed in a shopping area in the port city of Antwerp, a police chief said.
The man was "under the influence of something" but it was not clear what substance, a source close to the investigation told AFP.
Authorities were not certain if it was an attempted attack and the incident remained under investigation, several Belgian sources added on condition of anonymity.
The prosecutor's office said the man was a national of France, but a French police source told AFP he was Tunisian holding French residency papers.
The driver sped off after Belgian soldiers, who have been deployed around the country to assist the counter-terrorism fight, tried to stop the car.
"A short while later, a rapid intervention force from Antwerp police was able to stop the car," the statement said.
It was not immediately clear if the car contained any explosives.
The man was of north African origin and used a car with French registration plates, Antwerp police chief Serge Muyters said.
The incident came a day after an attack on the British parliament killed three people plus the attacker, as well as after the first anniversary of the Brussels attacks in which 32 people died.
"A vehicle with French plates has tried to drive at high speed into the Meir (shopping street). A man in camouflage was taken away," Muyters told a news conference.
"The pedestrians had to jump aside," he said.
"My gratitude on behalf of all Antwerp to the soldiers who have intervened, the police services and the special intervention force," Antwerp mayor Bart de Wever tweeted.
'Continue to be vigilant'
"We continue to be vigilant. Our security services did an excellent job in Antwerp, thanks," he tweeted.
Meir is the main shopping street in Antwerp's historic centre and is mostly pedestrianised. It is one of the most important shopping areas in the country.
With soldiers deployed at key sites, Belgium has been on high alert since March 22 last year when suicide bombers attacked Zaventem airport and Maalbeek metro station that left 32 people dead and more than 320 wounded.
Belgium suffered a further shock in August when a machete-wielding man shouting "Allahu akbar" (God is greatest) attacked two policewomen in the industrial town of Charleroi.
He badly injured one in the face, before a third officer shot him dead.
ISIS coming home
ISIS have claimed responsibility for a number of attacks using vehicles in Europe in recent months, including Wednesday's carnage in London.
Attackers rammed lorries into crowds in the French city of Nice in July last year killing 86 people and a Christmas market in the German capital Berlin last year.
On Wednesday, Belgium's King Philippe and Queen Mathilde led ceremonies commemorating the Brussels bombings, which were also claimed by ISIS.
Interior Minister Jan Jambon told AFP in the runup to the anniversary that tighter security had made Belgium safer safer than it was a year ago.
However he said it faced the threat of continuing radicalisation at home and from battle-hardened fighters returning from Middle East battle fields.
Belgium's federal prosecutor Frederic Van Leeuw told AFP in November that the cell that carried out the Brussels bombings, and was involved in the Paris attacks, had got its orders from high up in the ISIS command.
Numbering around 500, Belgium is the European Union's largest per capita source of so-called foreign terrorists, but Jambon said none had left the country for the Middle East since January 2016.