The incursion by an unmanned aircraft into Israeli airspace at the weekend exposed the weakness of Israeli air defences, an Iranian military official was quoted as saying on Monday.The Israeli air force shot down a drone on Saturday after it crossed into southern Israel, the military said, but it remained unclear where the aircraft had come from.Jamaluddin Aberoumand, deputy coordinator for Iran’s Islamic Revolutionary Guard Corps, said the incident indicated that Israel’s Iron Dome anti-missile defence system "does not work and lacks the necessary capacity”, Fars news agency reported.The Iron Dome system, jointly funded with the United States, is designed to shoot down short-range guerrilla rockets, not slow-flying aircraft. It intercepted more than 80 percent of the targets it engaged in March when nearly 300 rockets and mortars were fired at southern Israel, the Pentagon said at the time.The drone was first spotted above the Mediterranean near the Hamas-ruled Gaza Strip to the west of Israel, said military spokeswoman Avital Leibovich. An Israeli warplane shot it down above a forest near the occupied West Bank.Israeli parliament member Miri Regev, a former chief spokesman of the military, wrote on Twitter it was an "Iranian drone launched by Hezbollah”, referring to the Lebanese Shi’ite group that fought a war with Israel in 2006.