Despite growing international criticism of his government's bloody crackdown on illegal drugs, the Philippines top diplomat told world leaders Saturday that the rule of law governs the campaign to eradicate the illicit substances, which he said have stunted the country's development.

Secretary for Foreign Affairs Perfecto Yasay said President Rodrigo Duterte's crackdown is guided by a respect for human rights and the legal system, even though thousands of drug dealers and users have been killed in recent months.

"The rule of law and strict adherence to due process fully governs our campaign against corruption and criminality, including the fight against illegal drugs," he said.

More than 3,000 suspected drug dealers and users have been killed since July and more than 600,000 others have surrendered out of fear of being killed.

Despite growing alarm and international criticism, including from President Barack Obama and human rights watchdogs, the controversial Duterte has said he won't stop the campaign. He has said that killing drug suspects is lawful if police act in self-defense and urged citizens with guns to shoot and kill drug dealers who resist arrest. Witnesses have accused some police of gunning down people suspected of being involved in illegal drugs.

Yasay, who was addressing the U.N. General Assembly during its annual ministerial meeting Saturday, said the government is determined to eradicate the distribution, sale and use of illegal drugs because they threaten the country's peace and order "which, in turn, impedes our sustainable development goals."

Duterte, 71, overwhelmingly won election in May on the ambitious promise of eradicating corruption and crime, particularly illegal drugs, in six months. He recently said he underestimated the magnitude of the drug problem and will extend the crackdown by another half year.

Duterte said this week he will invite the U.N. chief and European Union officials to investigate his anti-drug effort, but only if he can question them in public afterward to prove their human rights concerns are baseless. He disclosed the offer in a speech Thursday in the Philippines in which he again lashed out at critics of his crackdown, including Obama. He accused them of hypocrisy for raising concerns about his anti-crime fight while launching military strikes that have killed innocent people in the Middle East.

Yasay acknowledged the scrutiny that the drugs crackdown has evoked from the international community.

"We urge everyone to allow us to deal with our domestic challenges in order to achieve our national goals, without undue interference," he said.