Canadian Prime Minister Justin Trudeau, a supporter of feminist causes, yesterday conceded for the first time that he had apologised in 2000 to a woman who accused him of groping her but insisted he did not feel he had done anything wrong.

Trudeau, whose government is working on new legislation against workplace harassment, has faced Canadian media scrutiny in recent weeks about what happened at a charity fundraiser in Creston, British Columbia nearly 20 years ago.

In his first direct comments on the incident on Canada Day last Sunday, the prime minister said he "didn't remember any negative interactions that day at all", but on Thursday he said "I apologized in the moment" without giving details.

According to an unsigned editorial in 2000 in the local newspaper, the Creston Valley Advance, Trudeau apologised to a local female reporter for inappropriately "handling" her.

The allegation resurfaced last month after Canadian political commentator Warren Kinsella tweeted a picture of the 20 year old editorial and used the Twitter #MeToo hashtag.

Many women in the United States and other countries have publicly accused men in business, government and entertainment of sexual harassment and abuse, giving rising to the #MeToo social media movement.

"I've been reflecting very carefully on what I remember from that incident almost 20 years ago and, again, I feel, I am confident, I did not act inappropriately," Trudeau, 46, told reporters in Toronto in televised remarks on Thursday.

Trudeau, citing the increasingly open discussion in society about sexual assault, conceded the woman in question could have come away from the encounter in August 2000 with a very different interpretation of what had happened.

"I do not feel that I acted inappropriately in any way but I respect the fact that someone else might have experienced that differently," he said. "If I apologised later then it would be because I sensed that she was not entirely comfortable with the interaction we had."

Trudeau said no one on his team had reached out to the women because they did not feel it was appropriate.

The woman told the Canadian Broadcasting Corp earlier this year that she was not interested in being associated with any further coverage of the story, and asked that her name not be used, and that she not be contacted about the story again. Reuters and other media have attempted to contact the woman as a result.

At the time of the original complaint Trudeau had not yet become involved in politics but was widely known to Canadians as the son of former Prime Minister Pierre Trudeau.

He attended the fundraiser in Creston to support avalanche safety. His brother, Michel Trudeau, was killed in an avalanche in 1998.