The Philippine president-elect has encouraged the public to help him in his war against crime and urged citizens with guns to shoot and kill drug dealers who resisted arrest.

Rodrigo Duterte told a huge crowd celebrating his presidential victory late on Saturday in the southern city of Davao that Filipinos who help him in the bloody war against criminality would be rewarded.

"Please feel free to call us, the police, or do it yourself if you have the gun, you have my support," Mr Duterte said in his nationally televised speech, where he warned about an extensive illegal drugs trade in the country that involved even police.

If a drug dealer resisted arrest or refused to be brought to a police station and instead threatened a citizen with a gun or knife, "you can kill him", Mr Duterte said.

"Shoot him and I'll give you a medal," he added.

Mr Duterte also asked three police generals based in the national police camp in metropolitan Manila to resign for involvement in crimes that he did not specify. He threatened to humiliate them in public if they did not quit, and said he would order a review of dismissed criminal cases of active policemen to rid their ranks of misfits.

The long-time Davao mayor and former government prosecutor said crimes were committed by law enforcers either because of "extreme greed and extreme need".

He said he would provide a small amount to an officer who was tempted because his wife has cancer or a mother died, but criminals motivated by extreme greed "will also be dealt with by me. I'll have you killed".

Mr Duterte, who starts his six-year term on June 30, repeated a plan to offer huge bounties to those who can turn in drug lords, dead or alive.

The 71-year-old won the May 9 presidential election on a bold promise to end crime and corruption within six months of his presidency. That vow resonated among crime-weary Filipinos though police officials considered it campaign rhetoric that was impossible to accomplish.

Human rights watchdogs have expressed alarm that his anti-crime drive may lead to widespread rights violations.

Mr Duterte has been suspected of playing a role in many killings of suspected criminals by motorcycle-riding assassins dubbed the "Davao death squads" but human rights watchdogs say he has not been criminally charged because nobody has dared to testify against him in court.