Belgian authorities have raised security in Antwerp after a car with French licence plates drove at high speed through a busy shopping street, forcing pedestrians to jump out of the way.
The federal prosecutor's office said the car was intercepted late Thursday morning at the port docks and a Frenchman was arrested.
Authorities then raised security in the centre of town, in places where people normally gather.
In the car, authorities said they found knives, a shotgun and a gas can with an unknown liquid.
The office said "because of these elements, and the events in London yesterday, the case is being taken on by the federal prosecutor's office," which usually deals with extremist attacks.
Belgian Prime Minister Charles Michel said "we remain vigilant. Our security services have done excellent work."
French President Francois Hollande confirmed the man was a French national.
"It seemed to involve a French national, with possibly a certain number of weapons in his boot - it's up to the judges to make a statement on that - who was looking to kill or at the very least create a dramatic incident," Hollande said.
The events happened a day after terror struck the heart of London and also come one day after Belgium held remembrance services for the Brussels airport and subway attacks, which killed 32 people on March 22, 2016.