Hundreds of monks rallied against United Nations Special Rapporteur on Myanmar Ms Yanghee Lee last week and Myanmar's most influential radical nationalist monk U Wirathu called her a "whore in our country".
"The sexist, insulting language used against the UN's independent human rights expert on Myanmar... is utterly unacceptable," UN human rights chief Mr ZeidRa'ad Al Hussein said in a statement.
"It is intolerable for UN Special Rapporteurs to be treated in this way and I call on religious and political leaders in Myanmar to unequivocally condemn all forms of incitement to hatred, including this abhorrent public personal attack against anUN-appointed expert," he added.
The monk's attack came after Ms Lee said the draft legislation, including curbs on interfaith marriage, religious conversion and birth rates, would be a further sign that Myanmar was "backtracking" in its democratic reforms if passed by parliament.
Activists say the proposed laws are particularly discriminatory against women and religious minorities.
High-level government support for the bills has raised fears over growing politicisation of religion in the Myanmar.
Mr Zeid said it was Ms Lee's job to address "key human rights issues and the situation of minorities in the country, particularly the Rohingya Muslim community."
The UN expert had in fact expressed admiration for the work of inter-religious leaders in the town of Lashio in Northern Shan State towards ensuring peaceful relations between communities, he said.
But, he added, she had also raised "serious concerns" about the draft legislation and about the situation of Rohingya Muslims displaced within Rakhine State and living in camps in difficult conditions.
On January 16, Ms Lee said acute tensions between Muslims and Buddhists in Rakhine, which has been wracked by violence since 2012, could have "far-reaching implications".
She also faced protests in Rakhine during her Myanmar visit, over perceived UN bias in favour of the Rohingya.
"Instead of attacking Ms Lee personally, I invite community, religious and political leaders in Myanmar to tackle the substance of her concerns," Mr Zeid said.
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