If the lockout of dockworkers in Montreal persists, there will be “catastrophic” consequences for the Canadian economy, particularly in Quebec and Ontario, the local port authority warns.

On Monday morning, Port of Montreal CEO Julie Gascon held a news conference, less than 12 hours after the lockout began.

The lockout is the latest escalation in a labour dispute that has heated up in recent weeks. The Port of Montreal moves $400 million worth of goods every day and is Canada’s second busiest port after Vancouver, which is also mired in a labour dispute. A lockout also began there last Monday.

On Thursday, the Maritime Employers’ Association (MEA) tabled what it described as a final offer, which came with a 72-hour lockout notice.

The MEA threatened to lock out workers as of Sunday at 9 p.m. if they didn’t accept the offer.

The dockworkers overwhelmingly rejected the offer, with 99.7 per cent of members voting against it, according to a spokesperson for the Canadian Union of Public Employees.

Gascon said it’s only a “matter of days” before the effects of the lockout are felt on a daily basis by everyday people, not just the workers. She said the lockout directly affects 1,200 workers at the port, but 10,000 other workers who depend on the port’s flow of goods, like truck drivers and marine pilots, are also caught in the dispute.

“Each container that is not moved here in Montreal is a missing piece in the Canadian economy,” Gascon said.

“Today, the lockout affects the logistics chain. Tomorrow, it’ll be the factories. After that, it’ll be the retailers.”

WATCH | The effects of the Montreal port lockout and other labour disputes: 

The Port of Montreal has said three terminals would remain operational in the event of a lockout: the Bickerdike terminal, liquid bulk terminals and the grain terminal.

The MEA has said its newest offer includes a three per cent salary increase each year for four years and a 3.5 per cent increase for the two subsequent years.

The increases would bring a dockworker’s total average compensation at the Port of Montreal to more than $200,000 per year at the end of the contract.

The association added that it is asking dockworkers to provide at least one hour’s notice when they will be absent from a shift — instead of one minute — to help reduce management issues “which have a major effect on daily operations.”

On Friday, an official with the dockworkers’ union, the Syndicat des débardeurs du port de Montréal, said the new offer only contains “cosmetic changes” and doesn’t address issues about scheduling, a major sticking point in negotiations.

The union is expected to hold a news conference later this morning.

This story will be updated.