Ottawa: A day after receiving sharp criticism over his brownface makeup photograph from a party 18 years ago, Canadian Prime Minister Justin Trudeau apologised, saying that he is "deeply sorry" for it.

According to Al Jazeera, Time Magazine published the photograph, just one week into an election campaign scheduled for October 21, where Justin is seeking his second term.

The photo showed Justin Trudeau, then 29, in a darker skin tone, wearing a turban and robes.

Trudeau, who is now 47, won the 2015 election with a landslide victory, is facing a lot of pressure over a corruption scandal and other controversies.

"I have worked all my life to try to create opportunities for people, fight against racism and intolerance," he told a televised news conference on his campaign aircraft.

"I can say I made a mistake when I was younger, and I wish I hadn't. I wish I had known better then, but I didn't, and I'm deeply sorry for it," the Canadian PM said.

"Now I recognise it was something racist to do," he said.

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Reacting to the controversy, Justin's opposition leaders condemned him for an act of "open mockery" and "racism" and called him "unfit for the rule".

Conservative Party leader Andrew Scheer said his Liberal rival is unfit to govern the country.

"I was extremely shocked and disappointed when I learned about Justin Trudeau's actions this evening," Scheer said.

Also, Jagmeet Singh, the leader of the third-place New Democratic Party, reacted by calling the behaviour "troubling" and "insulting."