Gunmen killed a brother of the founder of Lebanon's main Alawite party in an attack in the country's north on Monday, security sources and a spokesman for the party said.
Badr Eid, who was in his 60s, was shot as he drove through the Sunni village of Kuweikhat in Akkar region and later died of his wounds, the security sources said.
The assailants fled the scene in a vehicle, they added.
A spokesman for the party confirmed the death of Eid.
It was not immediately clear who was behind the attack.
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But his brother Ali Eid is the founder of the Arab Democratic Party, the most prominent Alawite political force in Lebanon now run by his son.
The Alawite community is an offshoot of Shiite Islam and is the sect of embattled Syrian President Bashar al-Assad, who is facing a deadly rebellion by mostly Sunni rebels seeking to topple him.
The northern Lebanese city Tripoli has seen frequent violence pitting gunmen in the Alawite district of Jabal Mohsen against neighbouring Sunni Bab al-Tebbaneh.
In January two suicide bombers killed nine people in Tripoli, hitting a cafe near Jabal Mohsen, in an attack claimed by the Syrian branch of Al-Qaeda.
Though the tensions between the two communities have their roots in the 1975-1990 Lebanese civil war, sectarian hatred has spiralled ever since the outbreak of a revolt in neighbouring Syria.
On Monday night the Lebanese army closed the roads between the two neighbourhoods.