First Nations demonstrators stopped passenger railway traffic lines between Toronto, Ottawa and Montreal today, while others stalled major highways and rail lines in parts of Manitoba, Alberta, New Brunswick and Ontario as part of the Idle No More Movement's national day of action.

Protesters also gathered in Windsor, Ont., near the Ambassador Bridge to Michigan, slowing down traffic to North America's busiest border crossing for several hours, the CBC's Allison Johnson reported.

Activities including rallies, blockades and prayer circles were staged across the country Wednesday as part of the grassroots movement calling for more attention to changes that were contained in Bill C-45, the Conservative government's controversial omnibus budget bill that directly affected First Nations communities.

Aboriginal leaders say there has been a lack of consultation on changes to environmental protection regulations.

Idle No More protesters set up a blockade east of Toronto, halting railway traffic for about five hours between Toronto, Ottawa and Montreal, Via Rail said. The demonstration blocked traffic between Belleville, Ont., and Kingston, Ont., Wednesday afternoon, affecting 10 trains and delaying more than 850 passengers. It ended at about 7 p.m. when protesters left the area without incident, Ontario Provincial Police said.

Rail line shut down in northern B.C.

In northern B.C., over 100 people from Gitwangak First Nation blocked a CN Rail line east of Terrace. CN Rail spokesman Jim Feeny said it is an important line that carries both passenger and freight traffic and links the port of Prince Rupert with the rest of North America.

The line was shut down due to safety concerns and at least one train was re-routed. The blockade, which began Wednesday morning, ended around 6 p.m. local time.

Earlier Wednesday, several hundred protesters on Vancouver Island blocked traffic on the Pat Bay Highway, which connects the Victoria airport with the Swartz Bay ferry terminal.

Traffic slowed at Ambassador Bridge

Meanwhile, area traffic near the Ambassador Bridge was slowed Wednesday afternoon, Johnson reported.

The Windsor, Ont., bridge is a key border crossing for trade between Canada and the U.S., she added, with roughly 10,000 trucks crossing daily.

Idle No More protesters gather near the Ambassador Bridge in Windsor, Ont. on Wednesday as part of the grassroots movement's national day of action. (CBC)

"Any flow of traffic stoppage is a pretty big deal, [but] we are told that is not the goal here today," she reported from Windsor.

Organizers said it was an "economic slowdown" and "not a blockade."

"We don’t want to inconvenience people too much, but we want to be in places that are going to get us noticed and allow us to get our information out," said organizer Lorena Garvey-Shepley.

Elsewhere in Ontario, Idle No More protesters set up a blockade near Highway 6 and Caledonia Bypass, according to CUPE.

In Toronto, demonstrators gathered in the downtown core near the British consulate. And in downtown Ottawa, crowds gathered outside World Exchange Plaza near Parliament Hill for a round dance.

Calgary-Edmonton highway blocked

In Alberta, a few dozen activists briefly delayed traffic on QEII, which connects Calgary and Edmonton, near Gateway Park, the CBC's Briar Stewart reported. Demonstrators from the Papaschase First Nation ended their protest at around 3 p.m. local time.

About 150 Idle No More activists in Calgary attended a candlelight vigil Wednesday evening outside city hall. Earlier in the day, protesters briefly disrupted traffic at a downtown intersection.

In Manitoba, Idle No More protesters gathered outside of the Manitoba Legislature. About an hour west of the city, protesters blockaded a railway line near Portage la Prairie, the CBC's Angela Johnston reported.

About 15 demonstrators, led by former Roseau River First Nation chief Terry Nelson, waved placards at a freight train early Wednesday morning, then took over the crossing, forcing another train to be halted by police at the scene. Service was stopped on the blocked rail line, which CN Rail spokesman Feeny described as a "critical link" in its network.

CN Rail obtained a court injunction to deal with the blockade, which it said was illegal, and protesters heckled officers serving the papers at the rail line. Although demonstrators initially said they would stay put, even if that meant they could be arrested, some left after the court injunction was given to the group.

Four protesters who remained blocked the Yellowhead Highway late in the afternoon, but they had left the area by 6 p.m.

Members of two Shoal Lake First Nations also blocked a section of the Trans-Canada Highway near the Manitoba-Ontario border for about three hours Wednesday afternoon. During the protest, Ontario Provincial Police kept one lane of traffic open to ease the congestion.

March across N.B. bridge in Miramichi

In New Brunswick, hundreds of demonstrators marched across a bridge along a major highway in Miramichi, the CBC's Jennifer Choi reported.

RCMP officers blocked the entranceways to Miramichi bridge from either direction as roughly 200 to 300 protesters marched, stalling traffic for nearly 2.5 hours, she added.

While many of the protests Wednesday were peaceful, Grand Chief Derek Nepinak of the Assembly of Manitoba Chiefs said he worried some protesters might take things too far.

"I think it's very important to recognize that we do not, at this time, condone the use of any kind of force," Nepinak said.

"We can't win in any kind of environment where we're using force."

Other chiefs said that today's action would be peaceful, but that if nothing changes to improve First Nations conditions, blockades would follow.

"At this time we have no plans to organize or facilitate the organization of roadblock on Highway 63 for Jan. 16 or any set date," said Chief Allan Adam of the Athabaska Chipewyan First Nation, referring to the northern Alberta highway to the oilsands region.

"However, the people are upset with the current state of affairs in this country and things are escalating towards more direct action."

PMO has no plans to revisit bill

First Nations activists are also planning a demonstration in front of the Canadian High Commission in London in the U.K. on Thursday.

A key demand of the protesters and chiefs alike is for the government to back down on changes to environmental oversight in two recent omnibus bills.

"The complete gutting of all environmental approval, regulatory and enforcement mechanisms in Canada … mean that the reassertion of aboriginal and treaty rights are the last best hope to protect both First Nations' and Canadians' water, air and soil from being poisoned forever by big oil and mining corporations," said Clayton Thomas-Muller from the Canadian Indigenous Tar Sands Campaign.

The government opposes any changes.

Andrew McDougall, Prime Minister Stephen Harper's spokesman, said: "The government has no plans to reconsider its legislation."

With files from The Canadian Press