Israel killed a senior commander of the Palestinian movement Fatah in Lebanon, accusing him of orchestrating attacks in the occupied West Bank.
In response, the Fatah party accused Israel of seeking to "ignite a regional war".
Khalil Maqdah was killed in a missile strike on his car in the southern Lebanese city of Sidon, according to Fatah and a Lebanese security source.
The Israeli military said that an air force aircraft struck Khalil Hussein Khalil Al-Maqdah in the area of Sidon in southern Lebanon.
The military said Maqdah was the brother of Mounir Maqdah, who heads the Lebanese branch of Fatah's armed wing, the Al-Aqsa Martyrs' Brigades, and accused them both of "directing terror attacks and smuggling weapons" to the Israeli-occupied West Bank.
It alleged that the pair "collaborate on behalf of" Iran's Revolutionary Guard.
The attack marks the first such reported attack on a senior member of Fatah, the movement led by Palestinian president Mahmud Abbas, in more than 10 months of cross-border clashes between Israel and Lebanon's Hezbollah group following the Gaza war.
Fatah said Maqdah had been killed "in a cowardly assassination carried out by ... Zionist (Israeli) warplanes on Sidon", describing him as "one of the leaders" of the Al-Aqsa Martyrs' Brigades in Lebanon, the movement's armed wing.
In a statement, it said Maqdah had "a central role" in "supporting the Palestinian people and its resistance" during the Gaza war and an "important role in supporting resistance cells" for years in the occupied West Bank.
The "assassination of a Fatah official is further proof that Israel wants to ignite a full-scale war in the region," Tawfiq Tirawy, a member of Fatah's central committee, told AFP in Ramallah.
Fatah supporters rally
Maqdah was killed in a strike on a car, said Fathi Abu al-Aradat, a senior Lebanon-based member of the Palestinian resistance group Hamas.
An AFP correspondent at the site of the attack said a car was struck near the Palestinian refugee camps of Ain al-Helweh and Mieh Mieh, adding that rescuers had pulled a body from the charred vehicle.
Dozens of angry Fatah supporters gathered inside the Ain al-Helweh camp, the AFP correspondent said, adding gunshots were fired in the air.
Hezbollah and its allies have exchanged regular fire with Israel in support of its ally Hamas since the Palestinian group's October 7 attack on Israel.
The Israeli attacks have killed some 593 people in Lebanon, according to AFP's tally.
Fatah has not announced any attacks on Israel from Lebanon since clashes began, nor has it mourned members killed by Israeli fire in Lebanon.
Source: TRT World