At least 25 people were arrested late Saturday after hundreds took to Montreal's streets, protesting against plans to raise tuition fees - as well as against the hosting of the Formula One Grand Prix.
The march began peacefully, with some of the 500 protesters banging pots and pans and some wearing carnival masks.
But when the marchers neared Crescent Street and its Formula One stands, they were blocked by police who used tear gas to disperse the crowd.
An AFP correspondent saw a young man dressed in black handcuffed by police and subjected to a body search.
The press service of the Montreal police said the arrests were targeted and more could be expected during the night.
Three police cars with broken windows and covered with graffiti were seen in the streets.
Earlier in the day, three protesters were arrested outside Grand Prix events.
A man and a woman who, according to police, carried "pyrotechnical devices," were seized at Jean-Drapeau Park, while another person was detained near a downtown metro station with a can of spray paint.
Students see Sunday's Grand Prix race as an "elitist event." But they also want to take advantage of the media presence and international visitors to publicize their fight against proposed tuition hikes.
However, La Classe, the student union considered to be the most radical of all, reiterated Saturday that it had no intention of disrupting the Grand Prix. Its spokesman, Gabriel Nadeau-Dubois, noted though that the organization was not able to control the behaviour of all the groups affiliated with it.
In a speech at the Festival of Solidarity in Montreal, Nadeau-Duibois also called on labour unions to band together with students to breathe new life into the protest movement.
Protesters this week also demonstrated against a special law passed by the Quebec government restricting the right to protest.
Special Law 78 requires organizers to give police at least eight hours advance warning of protest marches, with hefty fines imposed for failing to do so.
The measure was passed on May 18 in an effort to quell the demonstrations sparked by a plan to increase university tuition fees, but so far it has only served to galvanize opposition to the government.
Students have rejected a government offer to reduce the tuition hike by Can$35 ($34) per year, which would bring the total increase to Can$1,533 ($1,473) over seven years instead of Can$1,778 ($1,708).
Student leaders vowed to target the Grand Prix when talks in Quebec broke down last week after students rejected a government offer to reduce the planned tuition hike.
Since February, hundreds of protesters have been arrested and clashes have erupted sporadically as more than 165,000 students have refused to attend class and tens of thousands have taken part in nightly demonstrations.