A senior official of a Lebanese party which backs the Syrian regime was gunned down Thursday in the northern city of Tripoli, sparking deadly clashes, security officials said.
"Masked gunmen opened fire at 7:00 am (0500 GMT) on Abdelrahman Diab," an Alawite official in the Arab Democratic Party, an official told AFP.
He was killed as he drove through Tripoli, a hotspot of violence between supporters and opponents of Syrian President Bashar al-Assad.
The official said hooded gunmen on a motorbike carried out the assassination in a Sunni neighbourhood, shooting Diab in the head and stomach.
A party official confirmed the killing and said Diab was in charge of "military" affairs.
As news of the attack spread, one person was killed and eight wounded in clashes between Alawites in the Jabal Mohsen district and Sunnis the in neighbouring Bab al-Tebbaneh district.
The violence forced local schools and shops in parts of the port city to close, security sources said.
Since 2008, even before the outbreak of war in nearby Syria, more than 200 people have died in fighting between Alawite residents, who hail from the same religious sect as Assad, and Sunnis.
The tension between the neighbours goes back even further, stretching decades, but has been inflamed by the conflict in Syria, where Assad faces a Sunni-dominated uprising.
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The target of Thursday's attack, Diab, in his 50s, is the father of Youssef Diab, who has been detained by Lebanese authorities on suspicion of involvement in twin bombings of a Tripoli mosque in August that killed 45 people.
In a statement, the Arab Democratic Party implicitly accused supporters of Lebanon's new justice minister, Ashraf Rifi, of carrying out the killing, naming three men.
Rifi, the Sunni former head of Lebanon's Internal Security Forces, is an opponent of the Syrian government and its supporters.
The party said it held the government responsible for the crime and called on it to end attacks against Alawites, warning that the community would no longer tolerate being targeted.
"The current government is responsible for the shedding of Alawite blood in Tripoli," the statement said, calling for the arrest of the three men.
It gave "a 48-hour deadline to do this," adding "if the state and the security forces fail to do their job, we will not be silent."
The violence in Tripoli came a day after two suicide car bombs exploded near an Iranian cultural centre in Beirut, killing 10 people, according to an updated toll.
The attack was claimed by a jihadist group that said it was targeting the Shiite militant movement Hezbollah and Iran, a key ally of the Assad regime.
Lebanon is bitterly divided over the war in its larger neighbour, with the Iranian-backed Hezbollah having sent fighters to bolster Assad's troops while Sunnis have backed the Sunni-led rebellion.
The bombings and the violence in Tripoli highlight the challenges facing Lebanon's new government, formed at the weekend after a 10-month political vacuum.