Media playback is unsupported on your device Media caption "Long time ago" - Canadians react to Trudeau brownface images

Canadian Prime Minister Justin Trudeau has sought to put the blackface scandal behind him with an announcement on gun control as he seeks re-election.

Flanked by cabinet ministers he said his party would ban military-style assault rifles if they win next month.

His campaign went into damage control on Wednesday night following the publication of a photo of Mr Trudeau wearing brownface at a costume gala.

Two other similar instances were made public within hours.

Mr Trudeau fielded questions about those incidents for a third day, including about how he was dealing with displeasure at the revelations within his party's own ranks.

"I let them down, I let a lot of people down, and I'm very sorry for that," he told reporters in Toronto.

The Liberals need to hold onto their seats in the Toronto-region if they want to retain power, and the city has been struggling with gun violence in recent years.

The Liberal leader also sought to speak to opponent Jagmeet Singh, the leader of the left-wing New Democrats (NDP), who is a practicing Sikh and the first person of colour to head a major federal party in Canada.

Media playback is unsupported on your device Media caption "Round to the nearest five" - Voter confronts Trudeau over blackface

Speaking after the first photo was published by Time magazine, the NDP leader responded emotionally about the impact the photo could have on Canadians who are members of a minority group.

"The kids that see this image, the people that see this image, are going to think about all the times in their life that they were made fun of, that they were hurt, that they were hit, they were insulted, that they were made to feel less because of who they are," he said.

Asked on Friday about the invitation extended by Mr Trudeau, Mr Singh he said he was open to speaking with the Liberal leader if it is a "private conversation".

But he said he was only interested if the discussion were sincere and not part of "a Liberal PR campaign" to help Mr Trudeau overcome the political crisis.

US President Donald Trump also weighed in on the matter, saying it left him "surprised".

"And I was more surprised when I saw the number of times. And you know, I've always had a good relationship with Justin. I just don't know what to tell you."