MONTREAL -- Montreal police are investigating a confrontation between dockworkers and port managers that allegedly erupted in violence Wednesday night amid a longshoremen strike.

Montreal police received a call at around 7 p.m. that a crowd of dockworkers had threatened and attacked Montreal port executives and their security guards near the Olympic Stadium, said police spokeswoman Caroline Chevrefils.

"According to that information...the strikers made some threats and also harassed the executives. There were some assaults and also some thefts," Chevrefils said.

The longshoremen had left the scene by the time police arrived to take statements, with no charges laid so far, she said.

About two-dozen managers were exiting a shuttle bus after moving containers at the Termont terminal when a dispute broke out with at least 50 dockworkers in the stadium parking lot, said Martin Tessier, head of the Maritime Employers Association.

"We did train some management people (to handle containers). We didn't take people from outside to do the work, but nonetheless the union was not happy," Tessier said.

"It went bad," he said, adding that some wallets and cellphones were stolen.

"There is no provocation in the world that deserves any intimidation, physically or verbally."

The altercation Wednesday followed strikers' actions two days earlier to stall the exit of managers from the Termont terminal, Tessier said, leading to the decision to arrange bus transport between the port entrance and the Olympic Stadium parking lot some three kilometres away.

The strike, launched Monday by more than 1,000 workers and initially planned for four days, revolves around scheduling as well as working hours and technology.

Michel Murray, a spokesman for the Canadian Union of Public Employees, said Monday that longshoremen routinely work 19 days out of 21 due to heavy traffic through the port.

He said deploying executives to handle tasks on the waterfront traditionally carried out by longshoremen was an "affront" by the company that amounted to "an act of war."

The dockworkers have been without a collective agreement for nearly two years.

CUPE did not respond Thursday to requests for comment.

This report by The Canadian Press was first published July 30, 2020.