Philippine gets its own Trump

Trash-talking Philippine presidential favourite Rodrigo Duterte has warned he is prepared to cut diplomatic ties with the United States and Australia after their envoys criticised his comments about the jailhouse rape of a missionary.

Duterte also told the ambassadors to "shut their mouths", as controversy raged over his comments last week in which he said he wanted to have been the first to rape the Australian woman who was brutalised and murdered in a 1989 prison riot.

"If I become president, go ahead and sever (diplomatic ties)," Duterte, 71, said on the campaign trail on Wednesday night, referring to the relationships with the United States and Australia, two of the Philippines' closest allies.

Duterte, who while campaigning has called the pope a "son of a bitch" and promised to kill tens of thousands of criminals, recounted at a recent rally the attack on the Christian missionary as part of his tough-on-crime pitch to voters.

"I was mad she (the missionary) was raped but she was so beautiful. I thought, the mayor should have been first," she told the crowd.

Duterte was at the time mayor of Davao, a major city in the southern Philippines where he is accused of running vigilante death squads that have allegedly killed more than 1,000 people.

The front runner has at times on the campaign boasted about running the death squads, claiming they killed 1,700 people, but also denied any links to them.

Duterte has similarly offered varying responses to the rape comments, with his media team releasing a statement in which he apologised. But on the campaign trail, he has repeatedly told reporters he would not say sorry.

Australian ambassador Amanda Gorely criticised his remarks this week, saying on Twitter: "Rape and murder should never be joked about or trivialised. Violence against women and girls is unacceptable anytime, anywhere". US ambassador Philip Goldberg later agreed with her.

"Statements by anyone, anywhere that either degrade women or trivialise issues so serious as rape or murder are not ones that we condone," Goldberg said in an interview with CNN Philippines television.