MANILA - President Rodrigo Duterte said on Saturday (Sept 10) human rights activists should be criticising Myanmar's de facto leader Aung Sang Suu Kyi for the persecution of a Muslim ethnic group, rather than taking an issue with his bloody anti-crime drive.

"Suu Kyi is a Nobel Prize winner. Now, look, the Rohingya, they're being brutalised. They're stateless," he said in his usual rambling speech at a business conference.

Mr Duterte, 72, was again defending his violent crackdown on the narcotics trade, amid widespread criticisms over the brutal deaths of three teens, two at the hands of police.

"These human rights (activists) with all the hullabaloo," he said.

Police have killed at least 3,800 drug suspects since Mr Duterte took office in June last year and vowed to rid the Philippines of narcotics.

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Human rights groups said the death toll was closer to 13,000, with motorcycle-riding, masked gunmen believed to be sanctioned by police accounting for the bulk of it. Most of those killed were in poor, rundown neighbourhoods.

In western Myanmar, the number of Rohingya who have fled fighting has climbed sharply to 270,000, placing a huge strain on camps in Bangladesh where they are seeking shelter.

Ms Suu Kyi, a Nobel Peace Prize laureate for her long struggle against military rule, has come under increasing international criticism for the plight of the Rohingya.

Bishop Desmond Tutu of South Africa, also a Nobel laureate, wrote in a letter on Thursday that it was "incongruous for a symbol of righteousness to lead such a country" that "is not at peace with itself, that fails to acknowledge and protect the dignity and worth of all its people."