Alain Rochon, general manager of the Montreal taxi bureau, said his association has seized 40 vehicles used by UberX drivers since mid-February with the help of Montreal police.
"UberX is illegal and it's being monitored by the Montreal Taxi bureau," Rochon said Monday.
"For the past few weeks, we've been intervening."
Mayor Denis Coderre and the Quebec government have called the service illegal.
But UberX continues to operate in Montreal, and company officials say they intend to fight every vehicle seizure in court.
The introduction of UberX to Montreal has been a hotly debated topic at the municipal and provincial level, with cab drivers arguing the service is compromising their ability to make a living.
The company has asked the province to make clear rules about car sharing.
Seizures a waste of money, Uber says
Jean-Nicolas Guillemette of Uber Quebec said the vehicle seizures are a waste of time taxpayer money.
"What is happening is you have bylaw officers from the taxi bureau who have to call a police officer," Guillemette said.
"It takes time and it costs a lot of taxpayers money trying to fight it."
He said the company plans to continue to meet with elected officials to find common ground.
"I think Montreal and the taxi bureau will benefit by sitting down with us and creating a new regulatory framework, making sure we offer what the population wants."
Quebec Transport Minister Robert Poëti said the government is open to an agreement with Uber, which uses licensed taxi drivers, but not the UberX service, which doesn't require a taxi licence.
"With UberX, it's totally illegal right now and when you do something illegal in front of the law, you could have a few problems and seizing the car is one of the possibilities," Poëti said.
Uber says its UberX service costs users between 20 and 30 per cent less than a standard cab fare.
The company takes 20 per cent of the fare, leaving the rest to the driver.
Users' credit cards are automatically charged through the app — tip included — meaning no cash exchanges hands.
Such trips are not eligible under the insurance plans that cover licensed taxi rides, and opponents describe this as only one among many safety risks associated with the practice.
Uber, in turn, argues that developing a mobile app that lets customers hail nearby cars makes it a technology company rather than a transportation firm.