"I've always had a good relationship with Justin. I just don't know what to tell you": Donald Trump

US President Donald Trump said Friday he was surprised at decades-old images of Justin Trudeau wearing "blackface" makeup that have rocked the Canadian prime minister's re-election campaign.

"I am surprised," Trump told reporters. "I was more surprised when I saw the number of times."

"I've always had a good relationship with Justin. I just don't know what to tell you," Trump said, a day after the Canadian leader was forced to again publicly apologize for the embarrassing images that emerged in the media.

Trudeau, who heads the Liberal Party and is campaigning for re-election in October polls, said that he recognized it was "something absolutely unacceptable to do."

The images showed him wearing blackface makeup during the early 1990s and also at an "Arabian Nights"-themed party 18 years ago.

Trudeau also admitted to wearing similar makeup in his teens when he sang Harry Belafonte's 1956 hit "Banana Boat Song (Day-O)" at a high school talent contest.

Trudeau, the son of former Canadian prime minister Pierre Trudeau, acknowledged that his actions were "racist."

"The fact is that 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 comes with a massive blind spot," he said.