Prime Minister Justin Trudeau weighed in on sexual assault and harassment on Monday, calling the #metoo movement an "awakening" and saying that Canadians needed a mindset change to address the problem.

Trudeau sat down with CBC Radio host Matt Galloway for a one-on-one interview during a conference about the future of social policy in Canada, held at the University of Toronto.

Asked about the sudden outpouring of accusations of workplace sexual harassment in recent weeks, he recalled working at a sexual assault centre at McGill University as an undergrad student.

"I got to work first hand with an issue that 25 years later we're still just scratching the surface on," he said, adding later that. "there is still so much work to do."

Prime Minister Justin Trudeau talks with Metro Morning's Matt Galloway about the #metoo movement and the need to shift the conversation around sexual assault and harassment. 0:41

He also recalled, later in life, sitting at a dinner with a unnamed "prominent person" who was "complaining because they were on the board of some university."

"They were saying, 'One girl comes forward and you've ruined this young student's life for the rest of his life,'" Trudeau recalled.

"I said, 'Wait a second, what about the 99 young women who don't come forward and how their lives are ruined?'"

Tightening the rules

Trudeau contended with sexual harassment accusations in 2015 when two Liberals MPs were kicked out of caucus for their roles in a harassment scandal involving female New Democrat MPs.

He told Galloway on Monday that he has been "very, very clear" that there is zero tolerance for harassment on the Hill.

"We've done extensive training sessions and contracts signed by all members of our team, not just the MPs but the entire culture around our political party," he said.

The federal government also unveiled new legislation earlier this month that would crack down on harassment in federal workplaces.

Trudeau and Galloway in conversation at the University of Toronto on Monday. (David Donnelly/CBC)

Asked if legislation was needed that would protect Canadian workers outside of federal workplaces, Trudeau said that there were "probably a number of legislative fixes," but that a greater societal change was needed.

"For me, legislation is a tool and if it can be shown to be effective, but what we fundamentally need is a shift in mindset," he said.

The goal, he said, is, "to make sure that each and everyone of us is stepping up when there are comments, when there is harassment.

"The number of people who come out whenever there's news about this person or that person, a whole bunch of people shrug and say, 'Oh yeah, I wasn't surprised by that, we saw that coming for a long time.' Well why didn't you say something then?"