Canadian Prime Minister Justin Trudeau said he was "wary of being definitive" about the number of times he wore "blackface" since he did not remember the "recent pictures that came out".
On Wednesday, Trudeau apologised after Time Magazine published a photograph showing him in darkened makeup at a fancy dress party in 2001, labelling it "a dumb thing to do."
When questioned by reporters, Trudeau also admitted he had dressed up in darkened make-up when at high school and performed "Day O", a traditional Jamaican song about people loading bananas onto boats.
A third video obtained by the Canadian news network Global News appears to show him wearing dark makeup and a wig.
Speaking in Winnipeg, Canada on Thursday, Trudeau said he would continue his campaign but that he had let people down.
"I didn't understand how hurtful this is to people who live with discrimination every single day. I have always acknowledged that I come from a place of privilege but I now need to acknowledge that that comes with a massive blindspot," he said.
Speaking from his campaign plane after the Time photograph was published on Wednesday, he said:
"In 2001, when I was a teacher in Vancouver I attended an end-of-year gala where the theme was Arabian Nights and I dressed up in an Aladdin costume and put makeup on," he said.
"I shouldn't have done that. I should've known better but I didn't. And I'm really sorry."
Canadian Conservative Party leader Andrew Scheer said his Liberal rival was unfit to govern the country after the picture emerged.
"Wearing brownface is an act of open mockery and racism," Scheer told reporters in comments broadcast live from an airport in Quebec where he is campaigning for the October 21 national election.
"What Canadians saw this evening is someone with a complete lack of judgment and integrity and someone who's not fit to govern this country."
"Blackface" was used historically in 19th-century minstrel shows where white performers used darkened makeup to caricature people of colour.
The Time image was provided by Vancouver businessman Michael Adamson earlier this month. It appeared in the yearbook for West Point Grey Academy where Trudeau, then 29, was working at the time, the magazine said.
Canadian outlet Global News said the video they obtained was shot in the 1990s and was obtained from a source within the Conservative party.
Watch Euronews' The Cube report in the video player above.