MONTREAL - The Canadian Federation of Independent Business has sent a letter to Prime Minister Justin Trudeau warning of dire consequences if blockades that have disrupted rail service across the country continue.

CFIB head Dan Kelly is calling on Ottawa to work with the provinces and law enforcement to get trains back on the tracks as protests in support of Wet'suwet'en hereditary chiefs who oppose a natural gas pipeline in British Columbia enter their 14th day.

The organization, which represents 110,000 small and medium businesses, says agriculture and natural resources are most affected, but that retailers and wholesalers are increasingly feeling the pinch -- and have fewer financial resources to weather extended disruptions than large companies.

RBC economist Nathan Janzen says the blockades, which have shut down one-quarter of Canadian National Railway Co.'s network and clogged its system from coast to coast, are clouding the economic outlook for Canadian manufacturing. Canadian Manufacturers and Exporters CEO Dennis Darby says the crisis is stranding an estimated $425 million in goods every day, while CN has temporarily laid off 450 workers.

The call from the CFIB comes amid mounting criticism of the Liberal government from Conservative MPs and provincial premiers, with some demanding Trudeau denounce the blockades and articulate a plan to end the them.

Via Rail's Montreal-Toronto and Ottawa-Toronto routes remain closed due to a blockade east of Belleville, Ont., halting passenger trains.