Filipino leaders are normally respectful to the leader of the Catholic Church, where 80 percent of the 100 million people are followers.

But not the Philippine president-elect Rodrigo Duterte, who gave Donald Trump a run for money when it comes to insulting people in an election campaign and has backtracked after saying he would apologize for insulting Pope Francis..

Duterte will be sworn into office on June 30 for a six-year term, and says he was raised as a Catholic.

But he has said he will not personally apologise to Pope Francis for calling him a "son of a whore," The Telegraph reported.

That was after Duterte's spokesman has said on May 12 a trip to Rome was in the works, during which the president elect would "explain to the Pope and ask for forgiveness." He didn't include a schedule, but said that it was one of Duterte's "top priorities," according to Crux.

Duterte has earned the nickname "The Punisher" for his colourful language and anti-crime platform, and had previously said he would travel to the Vatican to say sorry for the jibe.

When he was announcing he would run for president, Duterte hit out at Pope Francis for the traffic jams his visit last year caused in Manila.

"It took us five hours to get from the hotel to the airport. I asked who was coming. They said it was the Pope. I wanted to call him: 'Pope, son of a whore, go home. Don't visit anymore'," said Duterte.

He announced on May 15 that he had changed his mind and decided to send a letter instead.

"No more, that's enough," he told reporters when asked if we would go ahead with the trip, Agence France-Presse reported.

The 71-year-old Duterte was the long-time mayor of southern Davao city. He swept to victory in the May 9 presidential election following an aggressive campaign in which he peppered speeches with foul language showing disrespect for figures of authority.

VOW TO KILL CRIMINALS

The tough-talking former mayor has vowed to kill 100,000 criminals and feed them to the fish.

His pledge to clean up the Philippines with his uncompromising stance on crime, includes bringing back the death penalty and issuing security forces with "shoot to kill" orders.

The Catholic Church is a strong opponent of the death penalty.

Some of his comments encouraging rape have enraged Filipinos and his comments on women make some of those made by Trump pale in the shade.

"I was angry because she was raped, that's one thing. But she was so beautiful, the mayor should have been first, what a waste."

The taunt was reported to have drawn only a smattering of laughter from the crowd and despite Catholic leaders condemning his remarks they had little impact on his popularity.

Duterte had later said he "did not intend to attack the Pope" and that his anger was directed at the government for causing too much disruption to people's lives during the visit.