The UN Human Rights Council on Wednesday launched a probe into the Gaza offensive, backing calls by the Palestinians to hold Israel to account despite fierce opposition from the Jewish state.
The decision came after a marathon seven-hour emergency session of the top UN human rights body, where the Israelis and the Palestinians traded accusations over war crimes.
The 47-member council backed a Palestinian-drafted resolution by 29 votes, with Arab and fellow Muslim countries joined by China and Russia, plus Latin American and African nations.
The United States was the sole member to vote against. The 17 abstentions were by the council's European members, plus Japan and South Korea.
The probe team, yet to be appointed, is tasked with reporting back to the council by March.
Israeli Prime Minister Benjamin Netanyahu's media office slammed it as a "travesty" that ignored violations by Palestinian Hamas Islamists.
"This investigation by a kangaroo court is a foregone conclusion," his office said.
US ambassador Keith Harper warned the vote would undermine ceasefire efforts.
"This resolution is not constructive, it is destructive," Harper said, noting it lacked "any semblance of balance" because it made no mention of Hamas' attacks.
Speaking for the European Union, Italian ambassador Maurizio Serra also criticised the failure to mention Hamas or recognise Israel's right to self-defence, despite last-ditch efforts by his team to have such language included.
The session was called by Arab nations and fellow members of the Organization of the Islamic Conference.
The council's membership rotates, and Israel is not currently part of the UN body. Non-members cannot vote but are entitled to speak.
Israeli ambassador Eviator Manor lashed out at countries that piloted the vote.
"Their Pavlovian instinct demands they react against Israel, in order to divert attention from their own human rights violations," he said.
"Hamas is committing war crimes when it fires rockets indiscriminately at Israel towns and villages. Hamas is protecting its launching sites with the civilian residents of Gaza. Another war crime," he said.
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"And this council sits in judgement of Israel? There can be no moral symmetry between a terrorist aggressor and a democracy defending itself," he added.
- Blame over 'war crimes' -
Palestinian Foreign Minister Riyad al-Maliki hit back.
"What Israel is doing is a crime against humanity," he said.
UN human rights chief Navi Pillay also said Israel's military actions could amount to war crimes, while at the same time condemning indiscriminate rocket attacks by Hamas.
"There seems to be a strong possibility that international law has been violated, in a manner that could amount to war crimes," Pillay told the council, citing attacks that have killed Palestinian civilians, including children.
She said Israelis also had a right to live without constant fear of rocket attacks.
"Once again, the principles of distinction and precaution are clearly not being observed during such indiscriminate attacks on civilian areas by Hamas and other armed Palestinian groups," she said.
The resolution condemned "the widespread, systematic and gross violations of human rights and fundamental freedoms" since Israel launched its offensive last month and called for the urgent deployment of an "independent, international commission of inquiry".
The Gaza offensive marks the worst violence since two spikes in conflict in 2009 and 2012, and has already claimed the lives of more than 685 Palestinians, most of them civilians, and 34 Israelis, 32 of them soldiers.
"Twenty-five Palestinians have been killed for every single Israeli. How far is this going to go?" Palestinian ambassador Ibrahim Khraishi asked.
"When we ask for a commission of inquiry, what we want to do is identify those responsible so they can be held accountable, so that we can shed light on the truth," he said.
Manor vowed that Israel would "destroy" Hamas' military infrastructure.
"However, the Gaza residents are not our enemies. Israel is fully committed to international law," he said.