The move comes as the Philippines' main anti-narcotics agency signed an agreement to deploy soldiers in operations targeting what it calls "high impact" and "high value" drugs targets.

Philippine MPs are also pushing for a new law that restores capital punishment for convicted drug felons and another that proposes lowering the minimum age of criminality from 15 to nine.

Mr Duterte's determination to intensify the crackdown that has left more than 7700 Filipinos dead, including children as young as five, comes as a new report accuses police of instigating and inciting the murders of mostly urban poor, under the cover the crackdown, and falsifying evidence to cover-up their unlawful killings.

"Our investigations into the Philippine 'drug war' found that police routinely kill drug suspects in cold blood and then cover up their crime by planting drugs and guns at the scene," said Peter Bouckaert​, emergencies director of Human Rights Watch, who wrote the report.

"President Duterte's role in these killings makes him ultimately responsible for the deaths of thousands," he said.

The Human Rights Watch's 117-page report titled License to Kill backs other investigations by rights groups and media outlets, including Fairfax Media, that lawyers say could amount to crimes against humanity, as defined by the International Criminal Court, of which the Philippines is a member.

Mr Duterte announced on January 30 he was suspending police anti-drug operations following the murder of a kidnapped South Korean businessman, allegedly by anti-drug police inside the national police headquarters.

At the time the President described the police force as "rotten to the core".

But Mr Duterte now says he needs more men to sustain the crackdown amid reports that drug dealers were returning to the streets.

"So I need more men. I have to call back the police again to do the job most of the time on drugs, not everyone," he told reporters.

Mr Duterte said he was forced to make the decision because military personnel are engaged in conflicts, including a new offensive against the communist New People's Army and Muslim kidnap-for-ransom gangs and terrorists in southern Mindanao and nearby islands.

The drug killings have polarised Filipinos who voted overwhelming to elect Mr Duterte in May, after he had campaigned pledging to wipe out the illicit trade within six months and that fish in Manila Bay would grow fat from the bodies of drug pushers.

The Catholic Church, the country's most powerful institution, last month called for "active non-violence" to protest extra-judicial killings under the guise of the crackdown.

But opinion polls show Mr Duterte's popularity remains high despite condemnation of the crackdown by the United Nations, the US and human rights groups.

Police last Saturday arrested Leila de Lima, a politician who last year led a Senate probe into the alleged extrajudicial killings of drugs suspects.

Amnesty International has declared her a "prisoner of conscience".

Police allege Senator de Lima was involved in receiving money from prison drug traffickers while she was justice minister between 2000 and 2016.

She has described the charges against her as "trumped up" to silence her criticism of Mr Duterte, whom she has called a "sociopathic killer" with a "criminal mind".

Laws to restore the death penalty and lower the age of criminality to nine - which will allow young children to be targeted in the crackdown - are expected to be passed by mid-year.

Mr Duterte's supporters who hold a majority in parliament this week dropped rape, plunder and treason from the death penalty bill to win the support of some lawmakers who were opposing it.

Some senior members of the government wanted the law to include rape so that Australian Peter Scully, who is on trial on in the southern Philippines on horrific child sexual abuse and cyber porn charges, could be executed if found guilty.

Mr Duterte declared in a recent speech that young children were becoming drug runners, thieves and rapists and "must be taught to understand responsibility".

"You can ask anyone connected with law enforcement. We produce a generation of criminality," he said.

Critics of the law, including opposition MPs and human rights groups, are appalled at the move, saying it will harm children without any evidence jailing children reduce crime.