The report found an "unprecedented" scale of destruction wrought by Israel in Gaza, including the deaths of more than 2,200 Palestinians and the whole or partial demolition of 18,000 homes. UN inspectors wrote that Israeli phone call and dud missile warnings to targeted Palestinians were ineffective in saving lives. Overall, in both the West Bank and Gaza, UN inspectors concluded that "impunity prevails across the board" for Israeli forces, and that Israel has a "lamentable track record in holding wrongdoers accountable."

The council's commission of inquiry found Palestinian armed groups possibly guilty of war crimes for indiscriminate firing of unguided missiles at Israeli population centers; six Israeli civilians and 67 Israeli soldiers died during the 51-day conflict. Inspectors also documented the summary executions of at least 21 suspected Gazan collaborators, which they said amount to war crimes perpetrated by Hamas.

The commission was chaired by former New York Supreme Court Justice Mary McGowan Davis, who said in Geneva on Monday that the devastation in Gaza "will have an impact for generations to come."

She replaced former chairman William Schabas in February 2014 after Israel pointed out that he had been paid for work he did for the Palestinian Liberation Organization in 2012.

Collecting material for the report was a challenge. Israel and Egypt refused to grant inspectors access to Gaza or to Israel; as a result, nearly all the testimony was gathered by Skype or video calls. Investigators had to rely on news reports, public information, medical records and satellite imagery to further round out their understanding, while also meeting with Israeli and West Bank Palestinian witnesses in Geneva and Amman.

'Strong indications'

In fine-grained examinations of Israeli air strikes in Gaza, the inspectors found "strong indications" of disproportionate attacks that could be considered war crimes. In one case, 19 members of the Al-Najjar family, including 11 children and five women, died in an Israeli airstrike on the family home on July 26 in Khan Younis. The Commission found there was no warning for this particular attack; survivors claimed there had been no militant activity in their building.

In Gaza, inspectors found Palestinian armed groups grabbed at least 16 detained suspected collaborators with Israel from a prison and executed them by firing squad in public, which were extrajudicial killings that "amount to a war crime."

The report directed strong opprobrium at leaders on both sides. In Israel, the report read, "the fact that the political and military leadership did not change its course of action, despite considerable information regarding the massive degree of death and destruction in Gaza, raises questions about potential violations of international humanitarian law by these officials, which may amount to war crimes."

In Gaza, the report noted that Hamas fired from heavily populated areas, but also noted that most of the tiny coastal enclave was built up, making such urban warfare near inevitable. The investigators noted Hamas leaders called on Palestinians to ignore Israeli warnings to evacuate their homes. The report noted that Hamas has little judicial process to examine war crimes violations, and the newly formed joint Hamas-Fatah government has not been able to exercise its jurisdiction.

'Israel does not commit war crimes'

Israeli Prime Minister Benjamin Netanyahu said Monday, "Israel does not commit war crimes. Israel is defending itself from a murderous terrorist organization that calls for its destruction and which has perpetrated many war crimes."

He noted that the United Nations has issued more condemnations of Israel than against all other nations combined.

Lt. Col. (Res.) Adv. David Benjamin, the Israeli army's former chief legal adviser for the Gaza Strip, told reporters Monday, "Really what bothers me is the equivalence, Israel on one side, Hamas on the other, both sides guilty of crimes," he said. "It really doesn't do justice to the Israeli efforts that were made."

Hamas ignores accusations

Hamas announced Monday that it "welcomes the United Nations condemnation of the Israeli occupation, for committing war crimes during its last aggression on the Gaza Strip in July 2014."

The Islamic movement did not acknowledge the accusations leveled against it.

The United Nations report is the latest in a slew of examinations of the summer 2014 hostilities. In late May, Amnesty International concluded that Hamas in Gaza tortured and executed suspected collaborators with Israel.

An Israeli report issued last week found the military was not guilty of war crimes, including one notorious incident in which Israeli airstrikes killed four children playing on a beach.

The UN report issued Monday found that the Israeli military justice system has only issued indictments in cases of theft, and that its investigation into the beach incident "does not appear to have been carried out in a thorough manner."

The report issued Monday will be formally presented to the Human Rights Council on June 29. It may be used as a guide for an inquiry into the summer conflict by the International Criminal Court, which Palestinians joined in April this year.