The head of the Philippines' powerful Catholic Church called for an end to the "waste of human lives" following a brutal week in President Rodrigo Duterte's drug war in which a 17-year-old boy was among dozens killed.



Police raids described as "one-time, big-time" saw at least 76 people shot dead, authorities said, as rights groups and legislators condemned the operation as an alarming "killing spree" in Duterte's flagship campaign.



On Sunday, the highest-ranking church official in the predominantly Catholic nation expressed concern about the increase in the number of deaths.



"We knock on the consciences of those who kill even the helpless, especially those who cover their faces with bonnets, to stop wasting human lives," Manila Cardinal Luis Tagle said in a statement read in Sunday masses in the capital.



"The illegal drug problem should not be reduced to a political or criminal issue. It is a humanitarian concern that affects all of us."

READ MORE: Philippine police 'dumping bodies' of drug war victims

Another church leader has ordered bells to be tolled every night for three months in a northern region to raise alarm over the police crackdown.

Archbishop Socrates Villegas of the Roman Catholic Church says church bells will be rung for 15 minutes across his northern religious district starting Tuesday to rouse a citizenry "which has become a coward in expressing anger against evil."

Duterte, 72, launched an unprecedented crackdown on illegal narcotics after winning the presidency last year on a promise to kill tens of thousands of criminals.

The church, one of the nation's oldest and most powerful institutions, had been among the few voices denouncing the deaths as polls showed Duterte continuing to enjoy widespread popularity.

During the 14 months Duterte has been in power, police have confirmed killing more than 3,500 people - insisting they acted in self-defence.

More than 2,000 others have been killed in drug-related crime and thousands more murdered in unexplained circumstances, according to police data.



The numbers saw a sudden spike last week with Duterte praising officers who shot dead 32 people in a single province and calling for more.



Following Duterte's call, at least 51 people were killed in various cities including a 17-year-old boy whose death on Thursday sparked a national furore.



Relatives of Kian Delos Santos released CCTV footage of the boy being dragged away by two officers as they questioned a police report that he shot at them first.

READ MORE: Police kill Reynaldo Parojinog and wife in drug raid

In Sunday's statement, Tagle called for nine days of prayer for people who have died in the drug war.

"Those with sorrowful hearts and awakened consciences may come to your pastors to tell your stories and we will document them for the wider society," he said.



Duterte has launched a broadside against priests and bishops in response to the church campaign to stop the killings.