Israel and Iran exchanged sharp criticisms at a meeting of the UN General Assembly's disarmament committee on Friday, accusing each other of being a major destabilizing force in the Middle East.Israeli Ambassador Alon Roth-Snir told the United Nations' First Committee that "Iran remains the most significant threat to the security of the Middle East and beyond."He reiterated his government's strong opposition to a historic nuclear agreement between Tehran and six world powers, saying it was "unlikely to stop Iran's relentless pursuit of a nuclear weapons' capability." He accused Tehran of continuing "vehement anti-Semitic rhetoric and threats against Israel."Iran UN Ambassador Gholamali Khoshrou in turn accused Israel, which is widely presumed to have the region's only nuclear arsenal, of being "the only impediment ... towards realizing a nuclear weapon free zone in the Middle East.""Israel continues to block all international and regional efforts to fulfill this goal," Khoshrou added.Iran says its nuclear program is purely for civilian purposes, denying allegations from the United States and its allies that it has sought to develop the capability to produce atomic weapons.