JERUSALEM (Reuters) - The Iron Dome air defense system has shot down 97 percent of Palestinian rockets it tried to intercept during the outbreak of fighting in Gaza since the end of last week, the Israeli military said, an improvement in the performance of the U.S.-backed system. Iron Dome first entered service in 2011 and fires guided missiles to hit incoming missiles and other short-range threats in the air, and Israeli and US defense officials have previously estimated it has an 85 percent success rate. This percentage rose to 90 percent in the 2012 Gaza war. Made by state-owned Rafael Advanced Defense Systems Ltd. with the support of US company Raytheon Technologies, the Iron Dome is designed to economize on costly interceptors by engaging only with missiles traveling in a trajectory to strike populated areas. An Israeli military spokesman said that the movement had intercepted 97 percent of these missiles during the escalation of the fighting with Islamic Jihad activists in Gaza since Friday, describing this as the best performance of the system so far. "We are working to improve our capabilities all the time," the spokesperson added. The spokesman said that Islamic Jihad had fired 580 rockets at Israel as of Sunday morning, adding that about 20 percent of them fell inside Gaza, while the rest reached the outskirts of Tel Aviv and Jerusalem. Some 30 Palestinians, at least a third of them civilians and two of them senior Islamic Jihad commanders, were killed in an escalation of the fighting over the weekend as rockets drove tens of thousands of Israelis to shelters. The clashes alarmed world powers and prompted Egypt to broker a truce. The fighting was contained to some extent by the fact that Hamas, the Islamist movement that rules the impoverished and besieged Gaza Strip, held back its fire. But the situation may erupt again on Sunday with the visit of Jews celebrating the anniversary of the establishment of two ancient temples, the Al-Aqsa Mosque compound.