The Philippines presidential press office said on Wednesday that Duterte responded to Zeid Ra'ad al Hussein in a speech on Tuesday night during the inauguration of a bridge in Oriental Mindoro province.
"Look, you have a big head but it's empty. There is no gray matter between your ears. It's hollow. It cannot even sustain a nutrient for your hair to grow," Duterte said, according to the transcript provided by his office.
The hostility between the two began when the UN criticized Duterte's anti-drug campaign -- which has led to thousands of deaths since he came to power -- over alleged extra-judicial killings, Efe news reported.
In November, Duterte threatened to slap Agnes Callamard, UN special rapporteur on extrajudicial executions, for criticizing the anti-drug campaign when she was on an unofficial visit to the Philippines.
In March, Al Hussein said Duterte's remark was unacceptable and he needed a "psychiatric evaluation".
His comments triggered protests from the Philippines government, which called them "irresponsible" and "disrespectful", saying that it set a dangerous precedent at the UN by insulting the head of a member-state.
Duterte said that he had been advised not to respond to the UN high commissioner but in the end decided to take "revenge".
Since coming to power in June 2016, Duterte has led an aggressive campaign against the drugs trade, which international rights groups say have led to the deaths of over 12,000 people.
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