Employers at Canada’s largest port have said they would lock out their workers after a negotiating deadline with the union had passed, potentially disrupting key shipments of the country’s coal, potash and beef.

The BC Maritime Employers Association said it would lock out more than 700 foremen at the Port of Vancouver at 4.30pm local time (00:30 GMT) on Monday because negotiations with their union, the International Longshore and Warehouse Union Local 514, had broken down.

The threatened lockout in Vancouver, on Canada’s west coast, comes at the same time as an ongoing strike at the Port of Montreal, the largest port in eastern Canada.

The employers association, which includes private-sector waterfront employers, said the lockout in Vancouver was preventative because the union had issued a strike notice for Monday. It said this was to “facilitate a safe and orderly wind down of operations” in anticipation of a strike.

But the union’s president, Frank Morena, said in a statement that workers had started their shifts and the union had only planned “limited job action” such as refusing overtime. The workers are also refusing to participate with “technological change implementation” connected to automation, according to the Canadian Press news agency.

The two sides have been in lengthy negotiations over a new labour deal with the help of a federal mediator. The issues include pay, working conditions and increased automation with each side accusing the other of bargaining in bad faith.

Crucial exports affected

The lockout will not affect bulk grain shipments, but it could halt coal, potash, forestry products and products shipped in containers such as pulse crops and meats.

The work stoppage would also affect the Port of Prince Rupert on the northern coast of British Columbia.

Reuters said a 13-day strike last year disrupted more than 6 billion Canadian dollars ($4.32bn) in trade at the ports of Vancouver and Prince Rupert.

It has alarmed regions and industries in landlocked parts of Canada.

The government of Saskatchewan, which exports grains, petroleum products and fertilisers, has asked the federal government to intervene and resolve the dispute. In the past, the government has resisted calls to interfere in collective bargaining.