What was to be the final day of hearings in Toronto on the controversial Line 9 pipeline was cancelled Saturday, as hundreds of demonstrators took to the streets to oppose energy company Enbridge's plan to reverse the oil pipe and increase its capacity to carry crude.

Enbridge Pipeline Hearings 20131019

Protesters demonstrating against Enbridge's application to reverse it's Line 9 pipeline rally outside the Metro Toronto Convention Centre on Saturday, where the National Energy Board was originally scheduled to hold hearings. (Chris Young/Canadian Press)

"They try to make it seem like we're not going to have a spill. And it's very likely that a spill will happen somewhere along this line," said protester Nigel Barriffe, who lives near Line 9 in northwest Toronto.

Enbridge was to make its closing submissions to the National Energy Board on its plan to reverse the line, so it would flow from Southern Ontario to Montreal, and increase its capacity to move crude oil.

But the National Energy Board announced late Friday that Saturday's hearings were off, saying the way the previous day's hearings ended raised concerns about the security of participants. Protesters were out in force for Friday's panel hearing, but there was no violence during that demonstration or Saturday's rally.

On Friday, protesters, many gathered under the banner of the Idle No More movement, first milled outside the Metro Toronto Convention Centre to rally against the Line 9 pipeline and to show solidarity with demonstrations at New Brunswick's Elsipogtog First Nation against a shale-gas project. They were eventually allowed in slowly, after the NEB determined that there were enough seats.  

Line 9 protesters in Toronto

Saturday's demonstration saw a crowd of hundreds of people winding through downtown Toronto. (CBC)

After an anti-Line 9 deputant completed her official submissions to the NEB panelists, the demonstrators began chanting and moving up to the front of the room toward the panel.

There was a brief scuffle with security. Then the NEB panel members were escorted by security and police out of the room, as was an Enbridge representative.  

The NEB didn't provide a date for when Enbridge will present the closing arguments that had been slated for Saturday.

Protest organizer Amanda Lickers said the NEB should have found a way to let Enbridge make its case in support of the reversal.

"I think that if they were really concerned about security, they could have still done it over the web.... There could have been ways to make the presentation happen."

Critics cite environmental risks

The panel heard this week from interveners stating the reversal would put First Nations communities at risk, threaten water supplies and could endanger vulnerable species in ecologically sensitive areas.

Jan Morrissey of a Toronto residents' group showed up early Saturday morning for the hearing, only to learn it was cancelled.

Morrissey said she's disappointed she won't get to hear Enbridge's final reply to arguments made to the board by critics of the reversal.

Enbridge Pipeline Hearings 20131018

The day before, protesters overtook the public hearings on Line 9, as NEB panel members were escorted out by security and police. (Mark Blinch/The Canadian Press)

"It's sort of like reading a book and not getting to see the last chapter," she said.

The pipeline reversal would increase the line's capacity to 300,000 barrels of crude oil per day, up from the current 240,000 barrels.

Enbridge has also asked for permission to move different types of oil, including a heavier form of crude from the Alberta oilsands.

Opponents say the crude Enbridge wants to transport is more corrosive and will stress the aging infrastructure and increase the chance of a leak.

But Enbridge has said what will flow through the line will not be a raw oilsands product — although there will be a mix of light crude and processed bitumen.

Line 9 originally shuttled oil from Sarnia, Ont., to Montreal but was reversed in the late 1990s in response to market conditions to pump imported crude westward.

Enbridge is now proposing to flow oil back eastward to service refineries in Ontario and Quebec. 

The company has experienced several devastating spills on its pipelines, including one in Michigan that leaked 3.3 million litres of oil into the Kalamazoo River and has already cost the company more than $1 billion. The U.S. Environmental Protection Agency believes there is at least 684,000 litres of bitumen still in the river.

With files from CBC News