A leader of the dominant Roman Catholic Church in the Philippines has ordered bells to be tolled every night for three months in a northern region to raise alarm over a renewed police crackdown that has left more than 80 drug and crime suspects dead in just a week.

Archbishop Socrates Villegas 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."

The church move adds to a growing outcry after more than 80 suspects were gunned down by police in metropolitan Manila and nearby Bulacan province in just three days last week, the bloodiest under President Rodrigo Duterte's brutal crackdown.