The lead investigator in a recent United Nations inquiry into the Gaza conflict warned on Tuesday that the lack of accountability for war crimes in he Middle East has “reached a crisis point” and is undermining any hope of peace.

The investigator, Richard Goldstone, made his comments here as he presented the Human Rights Council with his final report on violations of human rights and international law in the three-week war in Gaza last winter, which accuses both Israel and Palestinian groups of committing atrocities.

“A culture of impunity in the region has existed far too long,” Mr. Goldstone said. “The lack of accountability for war crimes and possible crimes against humanity has reached a crisis point; the ongoing lack of justice is undermining any hope for a successful peace process and reinforcing an environment that fosters violence.”

Mr. Goldstone said that the mission is “highly critical of the pusillanimous efforts by Israel to investigate alleged violations of international law and the complete failure of the Gaza authorities to do so.”

The 575-page report looked at 36 specific attacks in Gaza and a number on the West Bank and in Israel, concluding that both the Israeli Defense Forces and Palestinian armed groups committed war crimes and possible crimes against humanity. Israel, which refused to cooperate with the mission, said that the report ignored Israel’s right of self-defense and ignored the militants’ use of civilians as human shields.

Mr. Goldstone, a former South African judge, urged the 47-member Human Rights Council to adopt the report, which recommends that the Secretary Council require Israel to report within six months on the results of its own investigations into the reports’ findings. If no good faith investigations take place within that time, the report calls on the Security Council to refer the issue to the International Criminal Court.

Mr. Goldstone rejected accusations of bias and expressed regret that “the response to date of the Government of Israel avoids dealing with the substance of the report.”

Michael Posner, the assistant secretary of state for democracy, human rights and labor, released a statement saying the United States took the mission’s allegations seriously and encouraged Israel to use “meaningful” efforts to investigate “credible allegations.” However, he also described the report as “deeply flawed,” and said it failed to deal adequately with the asymmetrical nature of the conflict.