A UN war crimes investigation into the Israeli-Palestinian conflict in Gaza has found evidence that both sides committed "war crimes," the global body said Tuesday. The investigation led by former South African judge Richard Goldstone concluded that "Israel committed actions amounting to war crimes, possibly crimes against humanity," during the Dec. 27-Jan. 18 Operation Cast Lead against Palestinian rocket squads in the Gaza Strip. The report "concludes there is also evidence that Palestinian armed groups committed war crimes, as well as possibly crimes against humanity," by firing rockets at cities in southern Israel, the UN said. The investigators recommended that the UN Security Council require Israel to launch its own credible investigation into the conflict within three months. If that is not done, the investigators called on the council to refer the matter for action by the International Criminal Court prosecutor within six months. Israel, which has refused to cooperate with the investigation, rejected the report's conclusion. "The mandate of the mission and the resolution establishing it prejudged the outcome of any investigation, gave legitimacy to the Hamas terrorist organization and disregarded the deliberate Hamas strategy of using Palestinian civilians as cover for launching terrorist attacks," the Foreign Ministry said in a statement distributed by the Israel's mission to the UN in Geneva. Hamas has been accused by Israel of using human shields during the conflict. "Notwithstanding its reservations, Israel will read the report carefully," the Foreign Ministry said, noting that the IDF had examined more than 100 allegations regarding the conduct of its forces during the Gaza operation, resulting in 23 criminal investigations. Israel's Ambassador to the UN Gabriela Shalev told Army Radio that Israel "totally rejects" the report, saying it was "political and one-sided." "It's a difficult day when they make such baseless accusations against us," she said, adding, optimistically, that Israel had "good friends" in the UNSC, in addition to the US, that would listen to its side of the story. NGO Monitor President Gerald Steinberg told CNN that the UN mission probing the Gaza operation was essentially a "kangaroo court." The 575-page report, which was released ahead of its presentation to the UN Human Rights Council later this month, said Israel's attacks in the Samouni neighborhood of Zeitoun, south of Gaza City, including the shelling of a house where soldiers had forced Palestinian civilians to assemble, amounted to war crimes. It found that seven incidents where civilians were shot while leaving their homes trying to run for safety, waving white flags and sometimes even following Israeli instructions, as well as the targeting of a mosque at prayer time, killing 15 people, were also war crimes. A "direct and intentional attack" on the Al Quds Hospital and an adjacent ambulance depot in Gaza City "may constitute war crimes," the report said. Several Palestinians told the mission they were used as human shields by the IDF, the report said, noting the case of Majdi Abd Rabbo, a 39-year-old intelligence officer of the Palestinian authority who was forced to walk ahead of the troops as they searched his and his neighbor's house. Rabbo was forced to undress down to his underwear in front of the soldiers and his sons had to strip naked, the report said. On the Palestinian side, the report found that armed groups firing rockets into southern Israel from Gaza failed to distinguish between military targets and the civilian population. "Where there is no intended military target and the rockets and mortars are launched into civilian areas, they constitute a deliberate attack against the civilian population," the report found. "These actions would constitute war crimes and may amount to crimes against humanity." Investigators also called on Israel to immediately allow people and goods across borders "for the recovery and reconstruction of housing and essential services and for the resumption of meaningful economic activity in the Gaza Strip." They also recommended that Israel ease up on fishing restrictions within 20 nautical miles from shore and allow farming to resume within the Gaza Strip "including within areas in the vicinity of the borders with Israel." During a press conference Tuesday, Goldstone complained about the absence of Israeli cooperation, but hailed the report's objectivity. The report "should be judged on its own merit and anyone reading it should be impressed with its objectivity and independence," he said. Nine Israeli human rights groups called on the government to take the report seriously and not to reject its "legitimate" findings from the outset. "It's clear that the finding of the report, compiled after collecting information and testimonies from Palestinian and Israeli victims, join a long series of reports showing that Israel's actions during the fighting in Gaza, and those of Hamas, violated the rules of war and human rights," said the groups in a statement. "Human rights groups in Israel believe that the state of Israel must conduct an independent inquiry to look into these allegations and cooperate with an international monitoring mechanism that can ensure the impartiality of the investigation and the implementation of its recommendations." The statement went on to say that human rights groups had already called for the attorney-general to set up an independent body to investigate the IDF's actions during Operation Cast Lead, a request they said had been rejected out of hand.