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(Reuters) - About 3,000 workers of Canadian National Railway CNR.TO, the country's largest railroad operator, went on strike on Tuesday, labor union Teamsters Canada said after both parties failed to resolve contract issues.

"Conductors, trainperson and yard workers at Canadian National Railway are now officially on strike," the union said in a tweet bit.ly/2O10KW3.

Canada, one of the world’s biggest exporters of farm products, relies on its two main railways to move canola and wheat over the vast distances from western farms to ports. Crude oil shippers in Alberta have also increasingly used trains in the past year to reach U.S. refineries as an alternative to congested pipelines.

The union had issued a 72-hour strike action notice period to the company on Saturday after the talks reached a stalemate, setting the momentum for the first strike at Canadian National in a decade.

Teamsters Canada spokesman Christopher Monette had said on Monday the strike comes because workers are “hitting a wall on issues related to health and safety”.

The labor union’s Facebook account also shared pictures of dozens of CN workers carrying placards in support of the strike on the streets of Saskatoon, Saskatchewan.

CN workers voted in favor of a strike in September after negotiations failed to produce a contract. The previous collective bargaining agreement expired on July 23.

The union and CN did not immediately respond to Reuters requests for comment.