Police are cracking down protesters trying to disrupt a conference in Montreal on the development of northern Quebec.
The protest was declared illegal shortly before noon and police say between 50 and 75 people were arrested.
Security has also been beefed up at the convention centre near Old Montreal where the meeting is taking place.
Participants are being searched to prevent protesters from getting in.
The demonstration comes a day after hundreds of protesters clashed with police outside the convention centre as Premier Jean Charest gave a speech inside.
Friday's clashes resulted in 17 arrests and some of the most violent confrontations with police since protests over tuition hikes began more than two months ago.
At least six people were injured, including four police officers.