Participants were trying to call attention to pro-democracy demonstrations in Bahrain — and they criticized the racing circuit's role in that country.
One activist from Bahrain addressed the crowd, reminding it that officials went ahead with a race there in April despite harsh repression by the government. He said activists were being killed as race went on.
He said he was heartened by the Montreal protests this week.
"It's a stand that's appreciated by the people of Bahrain. The people of Bahrain felt much abandoned by the Western countries," said Naser Alraas, an Ottawa man who said he was arrested and tortured in Bahrain last year.
"Sports should support human rights first."
The Montreal demonstration was being monitored by a heavy police presence. Police were steering demonstrators east, as far away as possible from Grand Prix festivities in downtown Montreal.
By late Friday night police said they had made at least 12 arrests for alleged criminal acts and municipal bylaw violations.
Security is far tighter than usual in Montreal this weekend, as the Grand Prix festivities have become a focal point in the protest movement that has flared up in Quebec over recent months.
There is a noticeable police presence in the subway system — which some protesters have promised to disrupt on Sunday's race day.
Police lines have also guarded the streets around Grand Prix parties and officers have intervened quickly to halt protesters anytime they get too close. There have been dozens of arrests and one protest crowd Thursday was momentarily isolated under the controversial kettling tactic.
Some police officers were pelted with projectiles Thursday and Friday nights, and pushed back the crowd with billy bats and pepper spray. Authorities also set up barriers around the main street hosting Formula One Parties, Crescent Street.
Montreal Police Cmdr. Ian Lafreniere would not provide numbers Friday for the extra police officers — but he did confirm plans to beef up security in the subway system.
"I'm not going to share the strategy," he said. "For the weekend, you'll see a lot of police presence in subway stations and this is not only in the downtown ones — that will be in each subway station in Montreal."
The yellow metro line, which carries passengers under the St. Lawrence River onto the island where the race is being held Sunday, will get extra police attention.
"You can be sure that people who will go the Grand Prix will see a lot of police officers and we hope that everything will be fine," he said.
F1 boss Bernie Ecclestone made a brief, enigmatic reference to Bahrain during an exchange with reporters Thursday night. He sought to downplay this week's Montreal protests and compared them to more serious events in the Middle East.
"I heard about it," Ecclestone said after entering a Montreal cocktail benefit gala that had drawn protesters. "I didn't see anybody."
He said he had only one real fear this weekend — that somebody might try jumping onto the race track and get killed by a car.
"Otherwise I'm not frightened of anything to be quite honest with you," he said. "I've been in Bahrain where there are professionals."
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