Undeterred by a blessing from Pope Francis, Philippine President Rodrigo Duterte launched an angry rebuke of priests and bishops critical of his drugs war, accusing them of homosexuality, corruption and of abusing children.

Duterte was furious over concerns by the Catholic Church of alleged extrajudicial killings during his crackdown and lambasted clergymen for denouncing him instead of using their influence to get people off drugs.

His no-holds-barred tirade came a day after one of Duterte's top advisers met Pope Francis at the Vatican and said the Pontiff had told him he would bless the Philippines, and "also bless your president".

In a speech to policemen, the firebrand leader of one of only two majority Catholic Asian countries challenged the church to a "showdown" and threatened to expose priests and bishops for a litany of abuses.

"Most people here are Catholics. If you are a good priest, make them understand that they will die," he said, referring to drug users.

"You criticise the police, you criticise me. For what? You have the money. You are all crazy ... when we were making confessions to you, we were being molested. They are touching us. What is your moral ascendancy, religion? What is the meaning of it?"

The Catholic Bishops' Conference of the Philippines had no immediate comment when contacted by Reuters.

When we were making confessions to you, we were being molested

Pope's blessing

Duterte's aide, Jesus Dureza, was at the Vatican this week to deliver a letter from the president, thanking the Pope for his 2015 visit to the Philippines.

Duterte had famously called the Pope a "son of a bitch" for causing traffic snarl-ups, and later apologised, saying his remark was aimed at incompetent officials.

The Pope's blessing did not stop Duterte chiding the church, which is among a few institutions willing to oppose his war on drugs. Police figures show 7,042 people have been killed during the campaign, 2,250 in anti-drugs operations and most of the other deaths still being investigated.

Duterte said members of the clergy had wives and were engaging in homosexual acts, practices prohibited by the Catholic Church. Priests were also misusing state funds, he said, and they could not explain where vast amounts of money from public donations had gone.

"You expose me, fine. I expose you. Why? Your mistake is just all right, but ours is not? Bullshit. That is a big joke," he said.

"You asked for it. So if you really want a showdown, showdown. Make a change.

"If you cannot mend your ways, if you cannot even give justice to the small boys that you have molested in the past, you do not have that moral ascendancy to lecture on the sanctity of life."

Responding to Duterte's comments, Father Roy Bellen, a spokesman for the Archdiocese of Manila, said the church was aware of its weaknesses and despite limitations, it was fighting to root out its bad elements.

"Yes, there's still work to be done inside and outside of the church," he said. "We can never do everything, but whatever is in reach, we do it."