The UN human rights chief is backing the Goldstone Commission report that accuses Israel and Hamas of war crimes duding last winters Operation Cast Lead.
Navi Pillay's endorsement Thursday came even as Israel warned the scrutiny risked undermining Middle East peace.
Pillay said both Israel and Palestinians were ignoring the crimes committed by their fighters.
She said that holding war criminals accountable helps build trust that is needed for a durable peace.
Israeli Ambassador Aharon Leshno Yaar said the UN debate had "nothing to do with human rights" but rather with Palestinian politics.
Ibrahim Khraishi, the Palestinian Authority's UN ambassador in Geneva, said Israel had spurned his government's effort at reconciliation by delaying the vote two weeks ago.
President Shimon Peres blasted the Goldstone report in an earlier meeting with Spanish Prime Minister Jose Luis Rodriguez Zapatero in Jerusalem.
"Israel has investigated every war and action which it was compelled to undertake. We do not need outside judges," he said. "We will not allow a majority that is hostile to Israel to judge us. If the Human Rights Council wants to be fair, I suggest that it consider Iran's call for Israel's destruction."
He said a judicial tribunal "must be beyond reproach" and that there was no doubt that the Arab League and opponents of Israel had a majority on the council.
"If the UN wants to investigate let them first investigate Iran for its call for Israel's destruction. Iran is a UN member," stressed Peres. Ahmadinejad was recently received on red carpets in the halls of the organization. There is a limit to hypocrisy," the President said and added, "Why isn't Iran being investigated? Why does everyone remain silent?"
Peres called upon the UN once again to write a clear code for the conduct of the war on terrorism. He said that there was a code for the conduct of classical war, of army versus army, but there was no code for the conduct of a war on terrorism.
"Hamas fired missiles at homes, operated in the heart of the population and used children as human shields," he said. "No investigative committee, including Goldstone's, has provided an answer as to how to prevent Hamas's despicable terrorist acts against Israeli citizens."
