Uber drivers in Belgium were assaulted by fake clients this weekend, including by at least one cabbie angered by the lower cost rival, Belgian police said on Monday.
"Four individuals, including employees of the Uber company, were assaulted by four to six people," said a statement from city police in Brussels, the Belgian and European capital.
The assailants used the popular taxi app to lure the Uber drivers, the police said.
As in cities worldwide, the Uber car service is a bitter source of anger in Brussels, where it is blamed by traditional taxi drivers for offering unfair competition.
Earlier this month, hundreds of taxi drivers from Belgium and France brought central Brussels to a virtual standstill in a protest against Uber.
US-based Uber allows non-professional drivers to become chauffeurs-for-hire at rates far lower than normal taxi rides and is often unregulated.
In the events on Saturday night, once arrived at their pick-up location, the Uber victims were surrounded and their cars dumped on with flour and pelted with eggs.
"None of the victims in the incident were injured, but all were in a state of shock," the police statement said.
One man, a taxi driver, was arrested and told police he and the others, who are still unknown to authorities, attacked the drivers by posing as clients.
Uber is banned in Belgium but operates instead under the name UberPop under a law which allows individual vehicle hire.
Critics accuse Uber of flouting competition rules and of not carrying out sufficient safety checks on drivers and their vehicles.