Philippine President-elect Rodrigo Duterte said he will defy the Roman Catholic Church and seek to impose a three-child policy, putting him on a new collision course with the bishops a day after he called them "sons of whores."

The southern mayor has yet to be declared the May 9 poll winner, but an unofficial vote count by an election commission-accredited watchdog showed him ahead over his four rivals, three of whom conceded defeat. Duterte assumes office on June 30.

Duterte's often outrageous comments have won him huge support and his tirades about killing criminals and a joke about a murdered rape victim do not appear to have dented his popularity in the largely Catholic country.

"I only want three children for every family," Duterte said on Sunday in Davao City. "I'm a Christian, but I'm a realist so we have to do something with our overpopulation. I will defy the opinion or the belief of the Church."

About 80 percent of the Philippines' 100 million population are Catholics, the largest concentration of any Asian country, who oppose abortion and contraception.

On Saturday, he criticized the Church as the "most hypocritical institution," meddling in government policies and said some bishops were enriching themselves at the expense of the poor.

"You sons of whores, aren't you ashamed? You ask so many favors, even from me,"Duterte said in an interview broadcast by TV station GMA.

Monsignor Oliver Mendoza, spokesperson for the Archdiocese of Lingayen, whose head is the president of the Catholic Bishops Conference of the Philippines, said the Church respected Duterte's opinion but that it would continue to speak against government policies that are contrary to Church teaching.

Political analysts said that they were not surprised at Duterte's statements because some bishops spoke out against him during the election campaign.

"Like most liberal, secular politicians, Duterte is a deist," said Joselito Zulueta of the University of Santo Tomas.

He said Duterte's government was expected to clash more with the Catholic Church not only on population issues, but on the restoration of death penalty.