In a report, the UN special rapporteur on the occupied Palestinian territories, Michael Lynk, charged Israel with "the subjugation of (Palestinians') humanity" and intensifying a crackdown on human rights campaigners.
Lynk made the claims in a report presented to the UN rights council during the Geneva-based body's mandated session on Israel, known as Agenda Item Seven.
Israel is the only country targeted with a dedicated rights council agenda item.
The Jewish state and its supporters, notably in Washington, have repeatedly highlighted Agenda Item Seven as evidence of the council's credibility gap, arguing it cannot be effective while disproportionately targeting Israel.
President Donald Trump's administration has taken those concerns to the next level, with top diplomat Rex Tillerson publicly threatening to withdraw from the council over its "biased agenda item against Israel."
The State Department blasted the council again Monday for holding its Israel debate and vowed in a statement "to vote against every resolution put forth under this agenda item."
Washington also boycotted Monday's event that saw a group of majority Muslim nations repeatedly denounce Israel's treatment of the Palestinians.
The European Union condemned the continuing loss of life on all sides but voiced concern that Lynk's mandate and the Israel debate was one-sided.
Lynk's scathing findings were issued days after UN official Rima Khalaf resigned over another report in which she accused Israel of being an "apartheid state".
Khalaf, a Jordanian national, said she had resisted a request from UN chief Antonio Guterres to withdraw the report.
Trump's administration had demanded that the report by UN Economic and Social Commission for Western Asia be withdrawn and welcomed Khalaf's resignation.
Meanwhile, as part of its obligations under the Israel agenda item, Guterres's office presented its latest findings to the council on Monday.
"Chronic violations of international human rights law and international humanitarian law by all parties have persisted," the secretary general's office said, condemning Israel over settlement expansion among other offences.
Guterres faces heightened risks in taking on Trump's administration over Israel.
Washington funds roughly a quarter of all UN activities but Trump's initial budget proposal foresees significant reductions.
Guterres's office last week urged the US to rethink any "abrupt funding cuts."