(IsraelNN.com) Jurist Richard Goldstone, whose report to the United Nations accused Israel of war crimes, challenged United States President Barack Obama on Thursday over charges of bias. Obama's administration expressed concern that the report was both biased against Israel and flawed.

"I have yet to hear from the Obama administration what the flaws in the report that they have identified are. I would be happy to respond to them,” Goldstone told the pan-Arab news network Al Jazeera.

Goldstone noted that despite its criticism, the Obama administration had joined him in calling on both Israel and Hamas to conduct investigations in wake of the report.

Goldstone's report focused on Israel's Cast Lead counterterror offensive in Gaza in December 2008 and January 2009. The report mainly focused on Israel, which was accused of violating international law in a variety of ways, and also touched on terror group Hamas, which was accused of human rights violations as well.

The report was based largely on individual testimony and on information given by human rights organizations, among them groups known for their criticism of Israel such as Adalah and B'Tselem. Israel refused to cooperate with the report in an official capacity due to fears that the UN committee sent to research Cast Lead was fundamentally biased.

Hamas: Goldstone Never Blamed Us
Meanwhile, senior Hamas terrorist Moussa Abu Marzuk told the pan-Arab network Al-Arabiyya that Hamas had not come under Goldstone's criticism for its attacks on Israel. Marzuk, whose group was referred to in the report by the neutral term “Gaza authorities,” claimed that Goldstone had expressed concern over Hamas's treatment of political opponents, but had not accused the group of war crimes in connection to the firing of rockets at Israeli civilians.

The Goldstone report stated that: “It is the Mission’s view that the mortars and rockets [fired at Israel – ed.] are uncontrolled and uncontrollable, respectively. This indicates the commission of an indiscriminate attack on the civilian population of southern Israel, a war crime, and may amount to crimes against humanity.”

However, the report did not accuse Hamas in particular of launching these attacks, but rather expressed concern that Hamas had failed to prevent attacks conducted by “armed groups” within Gaza.

Marzuk said, therefore, that Hamas would conduct an investigation into the crimes which it was charged with in the report – namely, oppressing members of the rival Fatah movement. The attacks Hamas carried out against Israeli civilians will not be included in the probe.