Australia says rape and murder should never be joked about after the leading Philippine presidential candidate said last week that he "should have been the first" to assault an Australian missionary who was gang raped and killed by prisoners in 1989.

Davao City Mayor Rodrigo Duterte spoke at a campaign rally last Tuesday about the killings of 36-year-old Australian Jacqueline Hamill and four other missionaries in his city. She and other women hostages also were raped.

Duterte said he was angered because Hamill was so beautiful and the prisoners took turns raping her when "the mayor should have been first."

Ambassador Amanda Gorely tweeted late Sunday that "rape and murder should never be joked about or trivialized."