The Montreal Longshoremen's Union rejected a final offer made for a new labour contract, leading to a lockout being declared, the Maritime Employers Association (MEA) and the union said on Sunday.

The MEA said in a statement the lockout, which will impact nearly 1,200 port workers at the Canadian port that handled 8.7 million metric tons in the third quarter of 2024, has been declared as of 9 p.m. eastern (02:00 GMT).

The lockout will further slow Canadian imports and exports at a time the Port of Montreal was already operating at partial capacity and as West Coast ports are stopped due to a separate dispute.

The Port of Montreal is closed after terminal operators shut down operations over a labour dispute with the Canadian Union of Public Employees Local 375 in Montreal, Quebec, Canada, November 10, 2024. REUTERS/Peter McCabe

The union representing longshoremen at the Port of Montreal said the offer was rejected by 99.7% of members because the employer refused to negotiate.

"If the MEA had respected the collective bargaining processes, solutions would have been found and a conflict at the Port of Montreal would have been avoided," said union adviser Michel Murray in a statement.

Two terminals operated by Termont, the container terminal operator based out of the Port of Montreal, representing about 40% of Montreal's container traffic and 15% of total port volume, have been shut down by the union's strike, which began on Oct. 31.

However, after Sunday's announcement all longshoring at the port will be locked out. And only essential services not related to longshoring will continue at the Port of Montreal.

The MEA said that its final offer provided for a 3% salary increase per year for four years and a 3.5% increase for the two subsequent years.

West Coast ports including Canada's largest port of Vancouver have also been mostly shut down since Monday due to a labor dispute, impacting exports of canola oil and forest products.