UNITED NATIONS, Sept 21 (Reuters) - Philippines President Rodrigo Duterte said on Tuesday that anyone found to have "acted beyond bounds" in his campaign against illegal drugs would be held accountable under national laws, while appearing to reject an International Criminal Court probe. Duterte told the United Nations General Assembly he had instructed the Philippines Justice Department and police to review the conduct of the campaign, in which more than 6,100 suspected drug dealers and users have been killed since he took office in June 2016. "Those found to have acted beyond bounds during operations shall be made accountable before our laws," Duterte said in a video address to the annual gathering. Duterte made no mention of a formal investigation into possible crimes against humanity, which was approved by judges from the International Criminal Court last week, although he appeared to reject outside interference in human rights issues. "We have recently finalized with the United Nations our Joint Program on Human Rights. This is a model for constructive engagement between a sovereign Member State and the United Nations," he said. "Meaningful change, to be enduring, must come from within. The imposition of one’s will over another – no matter how noble the intent – has never worked in the past. And it never will in the future." Duterte"s government said last week it will not cooperate with the ICC or allow any investigators into the Philippines. read more Duterte and his police chiefs have said the killings were in self-defense and his government has insisted the ICC has no right to meddle in the country"s affairs. Rights groups say Duterte personally incited deadly violence in the drug war and accuse police of murdering unarmed suspects on a massive scale. Rights group say the police summarily executed suspects, which the policy deny. In February, the Philippine police said they were looking into a government review of the killings after the justice minister made an unprecedented admission to the United Nations of widespread police failures. read more