The Australian ambassador and Philippine presidential candidates have condemned the leading contender's remark that the mayor "should have been the first" to rape an Australian missionary who was assaulted and killed by prisoners in 1989.
Davao City mayor Rodrigo Duterte was speaking about the killings of 36-year-old Australian Jacqueline Hamill and four other missionaries during a hostage situation at a prison in his city.
Soldiers stormed the prison after learning that a male hostage had been killed and female hostages were raped.
All 16 convicts and five of the 15 hostages died.
"What came to my mind was they raped her, they took turns raping her," Mr Duterte said at a campaign rally last Tuesday.
"Why did I get angry - because she was raped?
"Yes, that's part of the reason, but also because she was so beautiful and the mayor should have been first."
His supporters attending the rally laughed and cheered at the comments, making Mr Duterte smile, as seen in YouTube video.
But other politicians and social media users criticised the comments.
Australia's ambassador Amanda Gorely tweeted that "rape and murder should never be joked about or trivialised" and "violence against women and girls is unacceptable anytime, anywhere".
Senator Grace Poe, Mr Duterte's closest rival according to recent surveys, said Mr Duterte's comment "is distasteful and unacceptable, and reflects his disrespect for women".
"You are a crazy maniac who doesn't respect women and doesn't deserve to be president," said vice president Jejomar Binay, another contender in the May 9 presidential election.
Former interior secretary and administration presidential candidate Mar Roxas said "anyone who laughs at the ultimate assault on the dignity of women should not be allowed to wield power".
Mr Duterte has refused to apologise for his comment, saying the gutter language was uttered in anger over the killing of the hostages in 1989.
But he apologised to the Filipino people because the hostage situation had turned violent and gory.
"It was said in anger, I was not joking," he said. "I said, this one, she's beautiful, like an actress, son of a bitch they beat me to her. Kill them all."
Mr Duterte has been nicknamed Duterte Harry after the Clint Eastwood film character because of his scant regard for rules.
The mayor casually threatens to shoot criminals, hang them or drown them in Manila Bay.
He built a political name with his iron-fist approach to fighting crime in southern Davao city, where he has been mayor for 22 years.