Israeli Prime Minister Benjamin Netanyahu urged world powers Sunday to reimpose tough sanctions against Iran, vowing to curb Tehrans regional "aggression" hours after another deadly strike on pro-Iranian fighters in Syria. "The International Atomic Energy Agency has determined that Iran refused to give the agencys inspectors access to secret sites where Iran conducted secret nuclear military activity," Netanyahu told his cabinet. The UN nuclear watchdog said Friday that Iran had accumulated enriched uranium at nearly eight times the limit under a landmark 2015 deal, and has for months blocked inspections at sites where nuclear activity may have taken place. Netanyahu accused Iran of "systematically violating its commitments by hiding sites, enriching fissile material and in other ways." "In light of these discoveries, the international community must join the US and reimpose crippling sanctions on Iran," he said. Iran has been progressively rolling back on its commitments under the 2015 agreement in response to US President Donald Trumps unilateral 2018 withdrawal from the accord and re-imposition of sanctions. The deal to curb Irans nuclear activities in return for sanctions relief was signed with the United States -- under Trumps predecessor Barack Obama -- along with Britain, France, Germany, Russia and China. Tehran has accused the remaining signatories of failing to sufficiently support it in the wake of Washingtons withdrawal. In his Sunday remarks, Netanyahu reiterated Israels longstanding vow to "act against Irans aggression" and "not let Iran obtain nuclear weapons". Israel "will continue to act systematically against Irans attempts to establish a military presence on our borders," AFP quoted him as saying. Late Saturday evening, at least 12 Iraqi and Afghan fighters in a pro-Iran base in eastern Syrias rural Deir Ezzor province died in eight strikes by unidentified aircraft. The Britain-based Syrian Observatory for Human Rights could not identify the aircraft, but said Israel was likely behind the attack.