MANILA (REUTERS) - Philippine President Rodrigo Duterte on Monday (Sept 18) invited the United Nations' human rights monitor to set up office in the country and join all anti-narcotic operations, amid growing public and global criticism of his bloody war on drugs.

"I will personally through an official channel invite the human rights commission to set up a satellite office here,"Duterte told reporters after attending the wake of a slain policeman, referring to the Office of the United Nations High Commissioner for Human Rights (OHCHR).

"I will tell police station commanders, do not operate without a representative of the UN human rights commission and everybody must wear a camera so it will all be transparent."

The comments were a marked change from Duterte's usual disdain for the United Nations, which he once threatened to withdraw from after UN human rights experts and rapporteurs expressed concern about the huge death toll in his signature war on drugs.

Thousands of people, mostly poor urban Filipinos, have been killed since he took office in June 2016.

The OHCHR had no immediate comment on Duterte's remarks.

Duterte has also made a public debate with UN envoys a prerequisite for any visit or investigation related to the anti-drug campaign.

His outreach to the UN comes as the Philippine National Police (PNP) comes under heavy criticism over the deaths in August of two teenagers. Police say they were killed in self defence, but activists and political opponents have said it was cold-blooded murder.

Duterte and his allies were chided last week after lawmakers allied with Duterte supported giving the Philippines Commission on Human Rights an annual budget of just 1,000 pesos (S$26), which critics at home and abroad said would be tantamount to destroying a constitutional body.

The firebrand leader in a speech on Saturday taunted CHR head Chito Gascon by asking him if he was gay, or a paedophile, and if he was "smitten with teenagers", referring to his comments about the latest incident.

Duterte on Monday said he had no plan to abolish the CHR.

He also said the proposed 678 million peso budget would be used to buy body cameras for the PNP during anti-drug operations, to show transparency.

More than 3,800 people have been killed in police anti-drugs operations in the past 15 months and at least 2,100 other homicides were likely drug-related. Police reject allegations by human rights groups that they are executing suspected users and dealers.