ISRAEL'S air force officially unveiled an unmanned spy plane overnight that experts said had been used in the Lebanon war and could potentially carry missiles for covert track-and-kill missions.

The Heron, which is manufactured by state-owned Israel Aerospace Industries (IAI), is billed as being capable of flying for 40 hours without refuelling at a maximum altitude of 30,000 feet and carrying 250kg of equipment.

Military sources said Herons first saw extensive combat actions during last year's Lebanon war, when they were used to relay footage of Hezbollah guerrillas to Israeli ground forces.

Israel has also deployed unmanned drones over the West Bank and Gaza Strip to help battle a six-and-a-half-year-old Palestinian uprising.

Foreign analysts said some of the drones have been used to assassinate Palestinian militants with onboard missiles.

Israel's air force has not confirmed such a capability exists.

"It would seem that the Heron is a very likely candidate to be an armed unmanned aerial vehicle," said Robert Hewson, editor of Jane's Air-Launched Weapons, adding that the drone's payload could be enough to fit as many as four guided missiles.

Some Israeli media have speculated that, given the Heron's range, it could be used to spy on arch-foe Iran's nuclear facilities. But Mr Hewson said this was unlikely.

"This is basically a propellor plane. If deployed over Iran it would soon be shot out of the sky," he said. -Reuters