Image copyright TIME MAGAZINE

The emergence of photos showing Canadian Prime Minister Justin Trudeau in "brownface" make-up has sparked strong criticism in the Canadian press and beyond.

The prime minister apologised on Wednesday night, saying he recognises the act was racist.

"I regret it deeply," Mr Trudeau said. "I'm deeply sorry I did that. I should have known better, but I didn't and I did that. I shouldn't have done that."

Commentators have condemned him and are asking what it means for his chances of re-election next month.

The CBC's Aaron Wherry says the photos raise questions over who Mr Trudeau "really is".

"There is no excuse for brownface," Wherry writes. "But it is perhaps particularly jarring to see Trudeau, a leader who has made diversity and acceptance central elements of his message and appeal."

Media playback is unsupported on your device Media caption Justin Trudeau told reporters: "I should have known better, but I didn't"

Mr Trudeau's only hope, Wherry says, is to say his record as prime minister shows it was an "aberration".

"The photo surely would have ended Trudeau's political ambitions if it had emerged during the 2015 campaign. The knock then was that he 'just wasn't ready,' that he was callow and lacked seriousness."

Christie Blatchford of the National Post also says the footage shows hypocrisy on Mr Trudeau's part.

"I am not someone who subscribes to the one-strike-and-you're-out rule," she writes. "But this is not how Trudeau has acted to the gaffes and mistakes of others... He is always quick to judge others, condemn them, and always with that rich Trudeau smarminess."

In the same newspaper, politics reporter Vanmala Subramanian writes: "Here you have a 29-year-old rich kid, a teacher nonetheless, who grew up with a famous dad... making a complete and utter mockery out of brown folk - people like me."

Maclean's senior writer Paul Wells writes that the incident has dealt a debilitating blow to the Liberal party's sophisticated election operation, fronted by Mr Trudeau's "Teflon-quality" and "smirky non-answers" to reporter's questions and the public's criticism.

"People change. People grow. Justin Trudeau's career has been based on claiming that simple fact for himself and denying it to his opponents. Will that stop now? Of course not. It's how he's wired."

Another article in the same title cites Professor Cheryl Thompson, who has studied the phenomenon of blackface in Canada. She told the magazine it "was not nearly so widely denounced in 2001 as it is now" and credits Mr Trudeau for apologising unequivocally, but says she hopes his colleagues will not "let him off easily".

The biggest problem is not Mr Trudeau darkening his skin for a costume, writes John Ibbitson of the Globe and Mail. The biggest problem is his silence.

"This election is about who voters should trust to lead this country in difficult times. How can they trust a leader who committed a racist act and then kept it hidden, hoping no one would find out?" Ibbitson says.

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As Ibbitson points out, the Canadian prime minister "is not one to apologise", though this time he had no choice - in an instance that may tank his chances for re-election.

"At the least, this furore will derail the Liberal campaign for several days. At the worst, it will permanently tarnish Mr. Trudeau's reputation in the eyes of some voters."

Political scientist Max Cameron told the Vancouver Sun that while Mr Trudeau's apology hit "all the right notes" it will still hurt him.

"He took responsibility for it and acknowledged the harm that this kind of behaviour can do. He clearly gets that this is a problem. But there's a question in my mind, 'Is this something you can come back from?' He embodies white privilege and he should have known better," Cameron writes.