An international human rights group on Sunday denounced Israel for failing to show that it will conduct an impartial investigation of reports that it committed war crimes during its deadly Gaza offensive last year. "An independent investigation is crucial to understand why so many civilians died and to bring justice for the victims of unlawful attacks," Joe Stork, Human Rights Watch (HRW) deputy Middle East director said in a statement. An independent investigation is crucial to understand why so many civilians died and to bring justice for the victims of unlawful attacks. In September, the United Nations Human Rights Council released a report by noted South African jurist Richard Goldstone, saying that both sides committed war crimes during the conflict, which killed about 1,400 Palestinians and 13 Israelis. But U.N. chief Ban Ki-moon said last week that the world body has not made a determination on whether both sides have done enough to investigate allegations they committed war crimes during the three-week conflict, which began at the end of December 2008. In a report, Ban outlines steps Israelis and Palestinians have taken to fulfill a U.N. demand for credible and transparent inquiries into civilian casualties. However, he concludes, "As such, no determination can be made on the implementation of the resolution by the parties concerned." Israel handed Ban a response outlining the steps the nation has taken to investigate charges of war crimes by its military during the course of the offensive in Gaza, which was aimed at stopping militant rocket fire into Israel. The Israeli military has "launched investigations into 150 separate incidents, including 36 criminal investigations opened thus far," according to the report. For its part, the Palestinian Authority said it had created a commission to look into various charges of abuses, but made clear that it did not view the potential wrongdoing on the Palestinian side as seriously as that allegedly committed by the Israeli military. "There is absolutely no symmetry or proportionality between the occupying power and the occupied people" wrote Riyad Mansour, Palestinian ambassador to the United Nations. In Gaza, the ruling Hamas movement released a summary of the steps taken to investigate wrongdoing, saying it had prevented militants from targeting civilians. But the rights organization dismissed the conclusion as "factually wrong." Human Rights Watch said it is still reviewing a full Hamas report. The group also said that Israel has a poor record of military investigations into alleged violations against Palestinians in Gaza and the West Bank. The Israeli human rights group Yesh Din has documented the low levels of criminal investigations, prosecutions, and convictions of soldiers despite the large number of allegedly unlawful deaths, it pointed out.