MANILA - The Catholic Bishops' Conference of the Philippines (CBCP) on Monday urged law enforcers to reject bounties for the death of suspected criminals and employ the shoot-to-kill policy only when faced with grave danger.

In a pastoral appeal issued by CBCP President and Archbishop of Lingayen/Dagupan Soc Villegas, the Catholic hierarchy expressed alarm over the rising number of reports of drug suspects getting shot by authorities because they supposedly resisted arrest.

The bishops reminded security forces that one can "shoot to kill" solely on the ground of legitimate self-defense or the defense of others.

"It is necessary to emphasize that you, as law enforcers, can 'shoot to kill' only first, when there is unjust provocation; second, when there is a real, not only conjectural, threat to your life or to the lives and safety of others; third, when there is due proportion between the threat posed and your own use of a firearm aimed at the threatening subject," the CBCP said.

The CBCP emphasized that killing a suspect outright is "not morally justified," no matter how much intelligence information may have been gathered against him.

"Suspicion is never the moral equivalent of certainty, and punishment may be inflicted only on the ground of certainty," the group said.

The Catholic leaders added that even when a suspect attempts to flee from law enforcers, every attempt should be made to spare his life unless his escape immediately puts others in harm’s way.

The CBCP also told law enforcers that it is "never morally permissible" to receive reward money for killing another person.

"When bounty-hunting takes the form of seeking out suspects of crime... one is hardly any different from a mercenary, a gun-for-hire, no matter that the object of one’s manhunt should be a suspected offender," the bishops said.

The CBCP also urged the public to report all forms of vigilante killings.

"We must all ask ourselves whether or not by our silence, our indifference, or worse, our acts, we may have contributed to the proliferation of crime and the increase in criminal activity," the CBCP read.

The pastoral letter concluded by saying, "Let no one ever raise his hand against his brother or sister, for the blood that is shed - even if it be the blood of one we suspect of crime - cries to heaven for justice."

Manila Archbishop Luis Antonio Tagle has issued an "oratio imperata" or special prayer for the country's leaders to shun a "culture of death" in the crackdown against crime.

(READ: Oppose 'culture of death,' Church prays for leaders)

The prayer did not name a specific politician, but President-elect Rodrigo Duterte has vowed to wage a "bloody" campaign against crime.

Since winning the elections last May 9, he has also promised to unleash security forces with shoot-to-kill orders and has offered a reward for police and citizens who will capture outlaws, "dead or alive."

Eager to burnish credentials for their new boss, police across the country in recent weeks have intensified the implementation of city ordinances like night-time curfews which have seen hundreds of people detained.

More than 40 drug suspects have also been killed since Duterte's May 9 election victory.

The Commission on Human Rights, several officials of the United Nations and other rights advocates have slammed Duterte for offering bounties for the vigilante killing of suspected criminals.