Quebec Public Security Minister Jacques Dupuis has ordered Montreal police to clear up subway security protocol, after an incident earlier this week in which public transit security guards watched a woman get beaten without intervening.

Dupuis called the event "intolerable" and asked on Wednesday that police and the Montreal transit commission sort out who is in charge of patrolling the city’s public transit system.

The incident in question occurred at the Berri-UQAM metro stop on Monday, the same day Montreal police announced they were taking over patrolling the public system.

The union representing subway security guards said the guards had no choice but to stand aside as the man assaulted his partner because police had ordered them to stop intervening in violent incidents.

"This shows how absurd this new arrangement is, because in regular circumstances, metro guards would have acted right away, but now they're not supposed to," union president Josée Massicotte told Radio-Canada.

Alain Lamirande told CBC's French-language service he witnessed a man beating up a woman who appeared to be his girlfriend on a platform at the Berri-UQAM station.

The Montreal resident said he saw the man punch and kick the woman, who fell to the ground. When he approached the security guards and asked for help, they "yelled back that it wasn't their responsibility anymore, they don't have to do anything about it."

Lamirande said he then went to the ticket station and asked the employee behind the glass whether she could call police. She answered "no," and said she was too busy to call her supervisor.

Police arrived 17 minutes later, but the couple had already left the station, Lamirande said.

Montreal police are assigning more than 130 officers to patrol the stations, saying it's part of a larger strategy to fight street gangs, who also operate underground in the transit system.

With files from the Canadian Press