Israel has voiced fears armed groups in Lebanon and Gaza would deploy exploding drones, in addition to their main rocket arsenals, against Tel Aviv in a future war, the chief of Israeli air defence said.

"We will have to cope with dozens of pilotless aerial vehicles, in both the northern and southern fronts," Major-General Shachar Shohat, told a Tel Aviv security conference on Monday.

Drones flew into Israeli airspace from Lebanon on at least two occasions in 2012 and 2013, apparently on photography missions and bids to probe air defences. Israeli jets shot them down.

The drones from Lebanon and Gaza would range from radio-controlled model airplanes weighing a few kilos to large drones with payloads of hundreds of kilos, Reuters news agency quoted Shohat as saying.

Another air force officer said Shohat was referring to drones carrying explosives and designed to crash into targets.

The reference to the heavier kind of vehicle, suggested Israel believes that Lebanon's Hezbollah group will receive such drones from Iran.

Hezbollah, Hamas and other Palestinian fighters have fired thousands of rockets at militarily superior Israel in previous conflicts, but have made scant use of drones.

Shohat, however, said that drones were now part of enemy strategies.

After the 2012 incident, Hezbollah leader Hassan Nasrallah acknowledged sending a drone that flew about 40km into Israel.

He said the drone's parts were made in Iran and it was assembled by Hezbollah members in Lebanon. Nasrallah has denied that Hezbollah or the Iranian Revolutionary Guards were responsible for the 2013 flight.

Israel is a world leader in drone technologies itself and has used the vehicles extensively in combat.

Uzi Rabin, an Israeli aerospace expert, said Israel's Iron Dome and Patriot missile interceptors were capable of shooting down most drones.

Israel is separately developing Iron Beam, a laser system for vaporising short-range mortar bombs and says it also will be able to destroy small drones.

Source: Reuters