Philippines president Rodrigo Duterte has threatened to “whack… in the head” any representative of the United Nations’s Human Rights Committee sent to observe his nationwide push to eradicate drug crime, calling those concerned about human rights during the infancy of his tenure “stupid.”

Duterte, the longtime mayor of southern Davao City — who won his position as head of state on a campaign vow to eradicate drug abuse and drug crime nationwide — has given police unprecedented liberties to detain drug crime suspects. He has become personally involved in the movement by naming 150 individuals in the government he claims to have evidence of having ties to drug crime. Over 60,000 Filipino drug abusers have surrendered to police and agreed to join rehabilitation programs since he took office in June, and hundreds have been arrested for ties to the drug trade.

Drug crime has decimated large swathes of the Philippines, particularly the impoverished south, where Duterte is from. The prime offending drug is methamphetamine, or “shabu,” which has grown increasingly popular among the nation’s youth.

The United Nations has expressed concern regarding Duterte’s empowerment of police to eradicate the drug problem, which Secretary General Ban Ki-Moon has condemned and the U.N. Office on Drugs and Crime referred to as an “apparent endorsement of extrajudicial killings.” Duterte has indeed told both police and civilians to kill drug offenders if they feel their lives are in danger.

Asked on Tuesday about the potential of the UN sending observers to the Philippines, Duterte said, “while I really do not know who’s going to come here for that, I am going to whack him in the head.”

“Do not investigate us as if we are criminals,” he added. “I will not receive you warmly in this country. But if you come here, explain or maybe hear about the happenings on criminals or see (for) yourselves.”

Duterte has insisted that he would cooperate with any justifiable probe of his government, however. “We are willing to submit ourselves for an investigation before anybody, but do not attribute acts of other criminals upon my government,” he said at a speech before national police. He has told police not to be “intimidated” by UN threats, however: “Do not hesitate to kill if you are in danger of losing your life.”

“UN can only investigate genocide, when you kill… killing children, killing the whole community… but when you kill criminals who fight you and criminals who fight among themselves, that is our duty,” he asserted.

Duterte has threatened to kill both domestic and foreign drug suspects if they do not comply with police. Most recently, he revealed a list of 150 people — 95 of them police officers, with mayors, congressmen, and judges on the list, as well — whom police had evidence of having ties to drug crime. Dozens of these have surrendered to police for investigation, which Duterte has applauded. Those on the list have been stripped of government protection following the killing of six officers in the line of duty when Duterte ordered the raid of Albuera mayor Rolando Espinosa’s home. Espinosa denies involvement in the drug trade despite his son being one of the most well-known drug traffickers in the Philippines.

The Philippine National Police (PNP) has moved not only to eliminate drug traffickers in its ranks, but drug abusers. On Wednesday, the PNP announced the firing of 18 police officers after failing drug tests. “It is disheartening to think that some police are involved in illegal drugs)… under my watch I will not allow this situation to worsen,” Director General Ronald dela Rosa said Wednesday.

Duterte has vowed to increase police salaries both as a reward for taking on a much larger mission at the start of his tenure and as a preventative measure to make drug crime less tempting to police. As a candidate, Duterte repeatedly blamed small salaries for police not doing their job properly and turning to drugs to be able to properly care for their families. The salary increase will occur no later than December, Duterte has promised.