Israel's military said the object was "apparently a balloon" and that officials were investigating.

Airline flights over Israel's south, between Tel Aviv and the Red Sea resort of Eilat, were halted during the encounter, the military said. No further details were immediately available.

Israel Radio reported the object was shot down near the Dead Sea, in the general area of the nuclear reactor, which is located next to the desert town of Dimona. Israel enforces a strict airspace quarantine around the facility.

"Air force planes were scrambled after a suspicious object was seen," a military spokeswoman said. "It was shot down." Local news site Ynet said one of the planes fired a missile at the object "which was hovering close to the nuclear research institute at Dimona."

It said the balloon appeared to be powered by an engine, but was unmanned.

Foreign experts have concluded that Israel has made nuclear weapons there. Israel's policy is to neither confirm nor deny it has nuclear bombs.

In 1986, an ex-technician at the Dimona facility gave documents and photographs to a British newspaper that led experts to conclude that Israel had hundreds of nuclear weapons at the time.

Israel considers the desert reactor a prime target for attack. The Dimona plant was built with French aid at the beginning of the 1950s.

Israel is not a signatory of the nuclear Non-Proliferation Treaty (NPT) and refuses to submit its nuclear facilities to inspection by UN watchdog the International Atomic Energy Agency.