Scuffles between police and protesters on the streets of Montreal last night just yards away from a big party event supporting the F1 Grand Prix of Canada led to at least 28 people being arrested, say reports from Canada.
Four police vehicles were reported to have been vandalised by spray paint and having their windows smashed, and police responded to being pelted by thrown objects from the crowd with blasts of tear gas and pepper spray as they moved in to contain the unrest.
The two-hour confrontation followed a running battle of wits between the police and a group of around 900 protesters moving through the city banging pots and pans. The incident lasted about four hours and finally calmed down after about 1am.
The protests originally started life over the raising of student tuition fees by the local Quebec government, but has since developed into more general social unrest over the state of the economy and against capitalism as a whole.
"This is not about school any more,” one local Montreal resident told reporters on Saturday. "I don't even call them protests, I call them anarchy."
Police said that the majority of arrests had been on assault charges, but around a dozen had been arrested under municipal by-laws rather than criminal violations. Police also interviewed a cab driver who allegedly drove his vehicle into a crowd of protesters - injuring three - but he was subsequently released.
With the Grand Prix being the area's biggest tourism draw of the year, it was inevitable that the race weekend would be drawn into the situation. Security at the Circuit Gilles Villeneuve has been stepped up as a result of the protests, with the traditional curtain-raising "open day' event earlier this week having to be cancelled.
Police are also expected to maintain a higher than usual presence on the streets of downtown Montreal on Sunday and in particular ensure that there is no disruption to the subway service to the Ile Notre Dame which is the main way spectators get to the race.
Police had to respond to a bomb threat at the Longueuil/Université-de-Sherbrooke station on Sunday morning that caused a brief disruption to the metro line shortly before 8am. The threat was a hoax and a 40-year-old man was subsequently arrested.