(CNN) Canadian Prime Minister Justin Trudeau apologized again on Thursday for wearing blackface in three separate incidents and said he did not know how many times he had put on racist makeup.

"What I did hurt them, hurt people who shouldn't have to face intolerance and discrimination because of their identity. This is something I deeply, deeply regret," he said.

Darkening your face, he added, "is always unacceptable because of the racist history of blackface . I should have understood that then, and I never should have done it."

Trudeau still insisted he was an ally in the fight for social justice and highlighted his administration's actions to fight racism and intolerance.

But he declined to say definitively whether there were more instances of him wearing dark makeup. He did not remember each instance, he said, because his privilege gave him a blind spot on the issue.

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