MONTREAL -- Tensions escalated at the Port of Montreal Monday morning as roughly 1,200 longshore workers walked off the job. 

The Canadian Union of Public Employees (CUPE) is going forward with its plan to hold a general unlimited strike, after giving notice last Friday.

This follows a pair of four-day strikes during the last two weeks by CUPE members that led to several ships being diverted to other ports, including Halifax and New York City. 

Union officials say a general strike was necessary, after the employers association cut overtime pay last week. The employers association previously stated the move was because night and weekend shifts had increased due to daytime strikes. 

"The employer changed our salary condition last week, they changed the [premium] of the night shift, and the weekend shift," said Michel Murray, a union representative with CUPE. "They put an economic pressure on the longshoremen."

Negotiations between CUPE and the Maritime Employers Association have been been ongoing for for more than two months. The workers have been without a collective agreement for nearly two years. 

According to the union, the main sticking points have been scheduling and wages. 

On Sunday, union officials said they had offered the employers association a 45-day truce to prevent a strike. A spokesperson for the association disputed that account, saying it had been the MEA who offered a truce which had been rebuked

The head of the Quebec Manufacturers and Exporters Association worries the strike will seriously impact Quebec’s economy, calling it 'bad timing'. 

"It's very unfortunate that the strike happens at this time, with COVID-19, manufacturers are really affected by this crisis," said Veronique Proulx, CEO of the Quebec Manufacturers and Exporters Association. 

"We're asking both parties of course to work closely and intensively together to have a positive outcome to the situation, but we’re also asking the federal government to see how they can better support and facilitate and to come to a negotiated and positive outcome for both parties."

Proulx and other business associations will be holding a press conference in Montreal Monday afternoon. 

Murray says he's not surprised by Proulx’s reaction. 

"The economic community every time there’s a strike somewhere they’re always very fast to ask for an intervention of the government," he said. 

Murray says the strike will continue until longshore workers have a new contract, or until a truce is reached with the employer where both parties are satisfied.