The incursion by an unmanned aircraft into Israeli airspace at the weekend exposed the weakness of Israeli air defenses, 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 defense 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.

Israeli defense officials have not confirmed this.

Aberoumand attributed claims the drone was made by Iran to a "psychological operation" by Israel, but did not confirm or deny them. "The Zionist regime (Israel) has many enemies," he added.

On at least one occasion, Iranian-backed Hezbollah has sent a drone into Israeli airspace. And in 2010, an Israeli warplane shot down an apparently unmanned balloon in the Negev near the country's Dimona nuclear reactor.

The Israeli military released a 10-second video clip of what it said was Saturday's mid-air interception, showing a small aircraft just before a missile from a fighter jet destroys it.

Israel has threatened to bomb Iran's nuclear sites if diplomatic efforts fail to stop the nuclear work it believes is aimed at getting weapons capability, a charge Tehran denies.

Iran has responded with threats to attack U.S. military bases in the region and retaliate against Israel if attacked.