Philippine President Rodrigo Duterte has hit out at "very stupid" United Nations criticism of his controversial war against illegal drugs that has claimed an estimated 1,000 lives, warning the global body not to interfere.

"Here comes the UN, easily swayed, and coming with a very stupid proposition," Duterte said in a speech on Wednesday at an event for police officers also attended by foreign diplomats.

"Why would the United Nations be so easily swayed into interfering in the affairs of this republic?"

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Duterte said that while the UN was quick to criticise his administration, the world body "is keeping silent" on the violence in the Middle East.

Referring to conflicts in the region, Duterte said he had not yet heard any public outcry targeted at "countries who are bombing villages and communities, killing everybody there, including the goats and the cows and the dogs".