Prime Minister Benjamin Netanyahu on Thursday accused Lebanon's Hezbollah of launching a previously unidentified drone which was shot down over Israel last week.
"We are acting with determination to protect our borders... as we prevented last weekend an attempt by Hezbollah," his office quoted him as saying during a visit to a newly-constructed section of the frontier fence with Egypt.
"We shall continue to act aggressively against all threats," he added.
Air force jets on Saturday shot down the unarmed drone over southern Israel's Negev desert after it entered the country's airspace from the Mediterranean Sea.
The military at the time dispelled the notion that the drone might have been launched from the Gaza Strip, and was looking into the possibility that Lebanese Hezbollah militants may have dispatched it, a military official told Israeli public radio.
Hezbollah chief Hassan Nasrallah was due to give an interview on the Shiite movement's television network at 1730 GMT in which he is expected to mention the incident.
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In July 2006, the Israeli military shot down an unarmed drone operated by Hezbollah over the Jewish state's territorial waters.
And on April 12, 2005, another pilotless Hezbollah aircraft succeeded in overflying part of northern Israel without being downed.
On Wednesday army radio and the top-selling Yediot Aharonot daily said the air force had only managed to shoot down the drone on the second attempt.
Both reports said that the first missile fired by the F-16 jet missed the drone which was eventually brought by a Panther missile, the military's most advanced air-to-air projectile.
A senior air force source quoted by Yediot played down the incident saying it was not unreasonable given the drone's small size.
"This is not a failure, no other army in the world with Israel's aerial defence systems could prevent the infiltration of such aircraft," he said.