The Israeli air force on Thursday shot down a drone from Lebanon off the northern coast of Israel in an incident described by Prime Minister Benjamin Netanyahu as "extremely grave."

It was the second such incident in less than seven months, and Israel's deputy defence minister putting the blame squarely on Lebanon's Shiite Hezbollah movement which had said it was behind a previous drone infiltration on October 7.

Hezbollah's television channel Al-Manar said on Thursday the group "denies sending any unmanned drone towards occupied Palestine," without elaborating.

"An unmanned aircraft (UAV) was identified approaching the coast of Israel and was successfully intercepted by IAF aircraft five nautical miles off the coast of Haifa at approximately 2:00 pm (1100 GMT) today," the Israeli military said.

The incident took place as Netanyahu was flying to attend a ceremony in the Druze village of Julis, some 32 kilometres (20 miles) northeast of Haifa, with the helicopter briefly landing after he received the news.

"I see this attempt to breach our borders as extremely grave," the premier said. "We will continue to do whatever we must to protect the security of Israel's citizens."

Military spokesman Lieutenant Colonel Peter Lerner told reporters the drone had been identified moving down the Lebanese coast before reaching Israeli airspace.

"A little after 1:00 pm, our aerial defence system identified (a drone) moving from north to south along the coast of Lebanon," he said.

"Aircraft, helicopters and combat airplanes were alerted to the area and after confirmation that it was an unfriendly aircraft, they were approved to shoot it down."

But despite widespread reports blaming Hezbollah, Lerner was cautious, saying the incident was still being investigated.

"We don't know where the aircraft was coming from and where it was actually going," he said, adding that the navy was "searching for the remains of the UAV" as part of the probe.

But deputy defence minister Danny Danon said it was clear that the Lebanese Shiite movement was behind the attack.

"We're talking about another attempt by Hezbollah to send an unmanned drone into Israeli territory," he told Israel's army radio, describing it as "another attempt to destabilise the Middle East."

Israel would respond to the incident in its own time, he said.

"We are ready and we will react as necessary," Danon warned. "They know not to provoke us."

On October 7, warplanes shot down an unarmed drone over Israel's southern Negev desert after it entered the country's airspace from the Mediterranean Sea, with Netanyahu blaming Hezbollah.

Several days later, Hezbollah leader Hassan Nasrallah confirmed his militants had sent an Iranian-built drone into Israeli airspace and claimed it had overflown sensitive sites in Israel.

He said the drone was "Iranian-built and assembled in Lebanon."

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 shot down.

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