VIENNA (Reuters) - Israel accused the UN nuclear watchdog chief on Thursday of political bias in his probe into allegations of a secret Syrian atomic site, and he shot back that Israel's position was "totally distorted". The International Atomic Energy Agency has sought to clarify US intelligence reports saying Syria almost completed a reactor of North Korean design that could have yielded plutonium for atom bombs, before Israel bombed it to pieces in 2007. IAEA head Mohamed ElBaradei has rebuked Syria for withholding documentation and access needed for inspectors to draw conclusions. But he has also criticised Israel for not alerting the IAEA before destroying the site, which he said has made it almost impossible to establish the truth. Those tensions boiled over into rare fireworks on the floor of an IAEA board of governors meeting when Israel's envoy accused ElBaradei of making "redundant" demands and showing bias by making repeated calls on Israel to produce more evidence. He said Israel had answered the only relevant IAEA question put to it by stating that uranium traces found at the bombed site did not come from Israeli munitions that hit it. "Therefore the repeated call by the director general on Israel to cooperate with this investigation is redundant," Ambassador Israel Michaeli told the 35-nation governing board. "Had (ElBaradei) wished for further information from Israel, he would have not refused to meet with Israeli officials, and (would have) refrained from publicly lashing at Israel. "Israel calls on (ElBaradei) to avoid political bias in dealing with the Syrian file," said Michaeli. Moreover, he said, ElBaradei had not used all "measures in his capacity" to make Syria open up to the investigation. He was alluding to "special inspections", a rarely used, coercive tool that IAEA officials have told Reuters would be premature and counterproductive in Syria's case. ElBaradei, departing from normal diplomatic reserve in public, called Michaeli's stance "totally distorted" and Israel's failure to elaborate on what it knew about Syria was "almost an insult to our investigative process." Looking straight at Michaeli, ElBaradei told him Israel's air strike had prevented the IAEA from carrying out its mandate to verify suspicions of nuclear proliferation in member states. "You, sir, mentioned that Syria should be deplored and condemned (by us). But Israel, with its action, is (to be) deplored by not allowing us to do what were are supposed to do under international law," he said. "You say we refrain from using tools. Israel is not even a member of the (non-proliferation) regime to tell us what to do. We would appreciate you stop preaching to us how we can do our jobs. We are using all tools available to us." Israel is one of only three countries outside the Non-Proliferation Treaty and is believed to have an undeclared nuclear arsenal, the only one in the Middle East. "You (Israel) cannot sit on the fence, making use of the system without being accountable ... I will continue to ask your government ... what information led you to circumvent the IAEA process," ElBaradei said. "To say I am biased -- I won't dignify that with a response." The IAEA agrees the uranium traces' origin was not Israeli and not part of Syria's declared inventory. Neither, it says, were similar uranium particles found later at a Damascus research reactor known to the IAEA and inspected once a year. Syrian envoy Ibrahim Othman dismissed the second find on Thursday, telling IAEA governors it was a vestige of innocuous neutron experiments by physics students. A senior UN official told Reuters that Syria's explanations remained unsatisfactory. ElBaradei, an Egyptian, will retire later this year after 12 years in office during which critics in Israel and the United States suggested he was "soft" on alleged nuclear proliferators. ElBaradei denied that and suggested Israel's atomic might has added to Middle East instability by spurring others, like Iran, Israel's arch-enemy, to seek nuclear weapons capability.