Israel denied accusations Wednesday that it was behind the assassination of a top Hezbollah commander and warned the Lebanese Shiite movement against any attack.
"If Hezbollah attacks Israeli territory our response will be firm and painful," Deputy Defence Minister Danny Danon was quoted by army radio as saying following the accusations.
Early on Wednesday, Hezbollah announced that Hassan Hawlo al-Lakiss had been assassinated during the night at his house in the Hadath region, east of Beirut.
"Direct accusation is aimed of course against the Israeli enemy which had tried to eliminate our martyred brother again and again and in several places but had failed, until yesterday evening," a Hezbollah statement said.
In response, foreign ministry spokesman Yigal Palmor told AFP "Israel has nothing to do with this.
"This is yet another Pavlovian response from Hezbollah, which makes automatic accusations (against Israel) before even thinking about what's actually happened," he added.
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Lakiss was the most senior Hezbollah figure to be assassinated since Imad Mughniyeh was killed in a Damascus bombing in 2008, which the group also blamed on Israel.
Both men were part of Hezbollah's secretive top leadership.
Israel's Energy Minister Silvan Shalom reiterated Palmor's denial, telling public radio: "Israel has nothing to do with this.
"Even if we're happy about it, it's the Salafists who have carried it out," Shalom said of extremist Sunni Muslim groups that oppose the Shiite, Iran-backed Hezbollah.
"It's a harsh blow for Hezbollah, which has tried to present the assassination (as Israeli) in order to distract from internal wrangling and divisions in Lebanon brought on by the Syrian" civil war, Shalom said.
Hezbollah's decision to intervene in Syria has fuelled tensions inside Lebanon, which is bitterly divided over the war.
Hezbollah emerged during Lebanon's civil war in the 1980s with the aim of driving Israeli forces out of the country and battled the Jewish state to a bloody stalemate in 2006.
Hezbollah said Lakiss's son was killed in the 2006 war, which claimed the lives of some 1,200 Lebanese, mainly civilians, and more than 150 Israelis, mainly soldiers.