10/10/2013 06:18 EDT | Updated 01/23/2014 06:58 EST

Protesters arrested at anti-Enbridge pipeline rally in Montreal

Three people have been arrested for allegedly assaulting police officers at a demonstration against  a controversial plan by Enbridge to reverse the flow of oil in the Line Nine pipeline from Sarnia, Ont. to Montreal.

Two more have been arrested under bylaw P6 — the municipal bylaw setting out rules for public demonstrations — and another dozen people have been ticketed under the provisions of that bylaw.

- Montreal hearings underway into pipeline proposal

The protest near Montreal's Victoria Square coincided with the third day of National Energy Board hearings into the proposal taking place nearby at the Palais des Congrès.

Montreal police declared the demonstration illegal at around 4 p.m. and dispersed the protesters.  The demonstration continued, however it has now been declared legal once again. 

Opponents say pipeline poses huge risks

On Tuesday, the first day of hearings into the Enbridge proposal, about 15 protesters were expelled from the conference room after disrupting the proceedings.

The project's opponents say they believe the project poses significant risks to communities along the corridor between Sarnia and Montreal.

If approved, the pipeline will be allowed to carry heavy crude originating in Alberta to eastern Canada.

Opponents worry about the impact of a potential oil spill near Lake Ontario and the St. Lawrence River or on valuable agricultural land.

Enbridge: economic benefits outweigh risks     

Enbridge argues the project would provide refineries in Quebec and Ontario with a more secure oil supply from Western Canada, at a lower price than foreign imports.

Quebec Premier Pauline Marois has agreed to create working groups to look into the economic benefits and environmental risks of the pipeline project.

She, too, has said it could be a boon for the province, producing jobs and boosting tax revenues.