MONTREAL -- The Port of Montreal may have to shut down because containers cannot be carried out of the port due to rail blockades, Quebec Premier Francois Legault suggested on Tuesday.

The premier's warning came as Canadian National (CN) announced the layoff of 450 workers, in Eastern Passage, Moncton, Charny and Montreal, due to the shutdown of rail service across eastern Canada.

The crisis must be resolved within days, Legault said. Otherwise, people will start noticing empty shelves in stores and experience shortages of some basic energy supplies.

"Right now in Belleville, Ontario, everything is blocked, and Mr. Ford and myself, we think it's enough for the negative impact on our economies," Legault said. "At this time, I think we can find a way to have a solution. I've seen and discussed with some communities, some indigenous communities. They want [us] to keep the railways open right away."

Opposition parties Quebec Solidaire and the Quebec Liberal Party urged Ottawa to reach a peaceful solution to the blockades. Interim Parti-Quebecois leader Pascal Berube said police intervention could trigger a negative reaction.

"If I'm blocking the railway, with other fellows, I'm not gonna be there for a long time," Berube said. "It's more sensitive because it's natives. We can understand that. They have a lot of rights, but they do not have the right to block railroads that are essential to our country."

A blockade in Kahnawake, south of Montreal, has snarled rail traffic on Canadian Pacific (CP) tracks. Another, in Tyendinaga, near Belleville Ont., has blocked trains from travelling between Montreal and Toronto. Those blocking the tracks are doing so in solidarity with Wet'suwet'en hereditary chiefs and their supporters who object to the passage of a natural gas pipeline through their traditional territory in northern British Columbia.