Iran's elite Revolutionary Guard said it has brought down an Israeli stealth drone above the Natanz uranium enrichment site in the center of the country.
"A spy drone of the Zionist regime (Israel) was brought down by a missile... This stealth drone was trying to approach the Natanz nuclear zone," the corps said in a statement on its official website sepahnews.com.
This act demonstrates a new adventurism by the Zionist regime... The Revolutionary Guard and the other armed forces reserve the right to respond to this act," the statement added.
An Israeli spokesman told AFP in Jerusalem on Sunday that the military does "not address foreign media reports".
Natanz is Iran's main uranium enrichment site, housing more than 16,000 centrifuges. Around 3,000 more are at the Fordow plant, buried inside a mountain and hard to destroy.
Israel has often threatened to attack Iranian nuclear installations.
Iran and the P5+1 powers -- Britain, China, France, Russia, the United States and Germany -- reached a six-month interim agreement under which Iran suspended part of its nuclear activities in return for a partial lifting of international sanctions.
In July, that deal was extended by four months, until November 24, to give the two sides more time to negotiate a final accord aimed at ending 10 years of tensions over Iran's nuclear program.
The sides remain split on how much uranium enrichment Iran should be allowed to carry out.
Washington wants Tehran to slash its program by three-quarters, but Iran wants to expand enrichment ten-fold by 2021, chiefly to produce fuel for its Bushehr nuclear power plant.
Israel, which Iran considers its sworn enemy, opposes any agreement allowing Tehran to keep part of its uranium enrichment program saying Iran would use the material to make an atomic bomb.
Iran has repeatedly vowed to wipe Israel off the map.
In 2010, the Israeli Air Force launched an unmanned aerial vehicle (UAV), dubbed "Eitan," "Heron TP" or "Heron 2", which can stay in the air 24 hours and can reach Iran.
“The ‘Eitan’ marks a technological breakthrough and a new level in the Air Force's ability to operate against threats, near and far, in its every day missions and during emergencies,” IDF spokesmen said.
Military officials declined to say whether the new UAV was designed for use against Iran and did not specifically mention the Islamic Republic, but foreign news services noted that the Eitan can fly as far as Iran.
"The launching of this airplane is another substantial landmark in the development of unmanned aerial vehicles.” Maj.-Gen. Nehushtan said. “They have gone from the humble beginning of their development, with initial operational results during the first Lebanon war, to the substantial and professional apparatus that now accompanies almost any air force operational frame work.”
The Eitan was grounded for much of 2012 following a mysterious crash during test flights.