The Philippines' top police chief who oversaw a bloody war on drugs that has killed thousands of Filipinos hinted on Monday at a possible run for the presidency.

Ronald dela Rosa, a stocky, celebrity-like general nicknamed "Bato" (Rock), who retires in 2018, has flagged his political ambitions, saying he was open to running for the Senate.

But in a speech after a flag raising ceremony at police headquarters, Dela Rosa for the first time publicly suggested he may have his sights set on higher political goals.

"Wait for Bato to become president and I will quadruple your salaries," Dela Rosa told his men as he denied rumours he would leave retirees out of planned salary increases.

Dela Rosa is among those touted by the national media as Duterte's possible successor in 2022, along with world boxing champion and senator Manny Pacquiao, and the son and namesake of late Philippine dictator Ferdinand Marcos.

Dela Rosa has acted as the enforcer for the firebrand leader's war on drugs which had led to more than 3,900 people killed in 16 months.

The campaign has sparked outrage abroad, but domestic polls have shown crime-weary Filipinos are largely supportive of the measure.

Duterte ordered the police this month to halt activities in the war on drugs and leave all operations to drug enforcement agency, amid unprecedented scrutiny of police conduct.

Police reject allegations by activists they are executing suspected drug users and dealers, saying victims in their anti-narcotics operations were killed because they were armed and had violently resisted arrest.