(Bloomberg) -- A strike that paralyzed trade out of Canadian west coast ports was declared unlawful hours after it resumed upon the union’s rejection of a tentative deal.

The Canada Industrial Relations Board issued the ruling Wednesday, ordering the International Longshore & Warehouse Union to cease and desist from participating in any strike action because the union didn’t provide 72 hours notice.

“This strike is illegal,” Labor Minister Seamus O’Regan said in a tweet accompanied by the text of the decision.

The ILWU caucus voted down the terms recommended last week by a federal mediator, the union representing 7,000 workers said in a release Tuesday, sending workers back on strike. It meant the resumption of a dispute that has stalled trade at coastal ports including Vancouver, Canada’s busiest — disrupting an estimated C$10.5 billion ($8 billion) in shipments, according to the city’s board of trade.

Resumption of picketing is already being felt in the agricultural sector. Canpotex, the Canada-based joint venture of Nutrien Ltd. and Mosaic Co., said Wednesday it’s withdrawing all new sales offers given the renewed disruption.

Alberta Premier Danielle Smith and business groups including the Canadian Chamber of Commerce have called on the federal government to draft legislation to force the workers back. So far, Prime Minister Justin Trudeau’s government has been reluctant to do that, given that it has an alliance in parliament with a union-friendly opposition party. 

An tentative four-year agreement was reached on July 13 between the union and the BC Maritime Employers Association with the support of the federal government. But it was subject to ratification by both sides.

“In rejecting this tentative agreement, ILWU leadership is choosing to further harm Canada’s economy, international reputation and most importantly, to Canadians, their livelihoods and all those that rely on a stable supply chain,” the BCMEA said in a release.

The union’s main sticking points appear to be the length of the agreement and pay raises. The four-year agreement is “far too long” given today’s uncertain times and employers have “not addressed the cost of living issues” that workers have faced, the ILWU said in a statement.

Job security was also a major concern. “The ILWU Canada Longshore caucus does not believe the recommendations had the ability to protect our jobs now or into the future,” the group said.

The employers’ association said the proposed deal included considerable hikes in wages and benefits, “over and above” the more than 10% boost received over the past three years and generally higher than recent private and public-sector union settlements in Canada.

At the outset of the strike on July 1, the union’s main goals were to stop the contracting out or outsourcing of maintenance work to third parties, protect workers from the impact of automation and get pay hikes that keep up with the rate of inflation and higher cost of living.

Shorter contract periods have become a common theme in recent collective bargaining because they minimize future risks for both employers and employees if inflation continues to cool, or stays elevated longer. The average duration of agreements in Canada’s transportation sector this year is 24 months, compared with 42 months last year.

Wage settlement data in 2023 for the industry showed an average pay raise of 3.3% in the first year, and a 3.1% average annual adjustment. But other dockworkers have gotten an annual increase of more than 7%.

The strike action earlier this month halted about C$800 million worth of cargo each day and a sustained strike will affect more than 115,300 jobs throughout the supply chain, Victor Pang, interim CEO of the Vancouver Fraser Port Authority, said in a release. 

“It will take months to recover from the operational impact of this strike action — the longest at the port in 50 years— and any sustained strike action will jeopardize Canada’s reputation as a stable trade destination.”

(Retops with ruling and statement from labor minister, adds new details and quotes throughout.)

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