A senior official in a Lebanese Alawite party supportive of Syrian President Bashar al-Assad was shot dead in the northern Lebanese city of Tripoli Thursday, a security official told Agence France-Presse, Al Arabiya reported.
"Masked gunmen opened fire at 7:00 am (0500 GMT) on Abdelrahman Diab," said a senior official in the Arab Democratic Party.
A party official said Diab was in charge of "military" affairs.
The almost three-year Syrian conflict has accentuated sectarian differences in Lebanon.
Tripoli has witnessed a rise in clashes between Sunnis who support Syrian rebels battling the Assad regime and Alawites who back the Alawite-dominated Syrian government.
The assassination of the official comes after six people were killed and more than 129 others were wounded in two explosions that hit a southern area of the Lebanese capital on Wednesday.
The Abdullah Azzam Brigades, an Al-qaeda-linked group that has claimed previous bombings in Lebanon, said it was responsible for the attacks in Bir Hasan, a residential and commercial neighborhood that is home to the Iranian and Kuwaiti embassies.
Beirut's southern suburbs, a stronghold of the Lebanese militant movement Hezbollah, have also been hit by seven bomb attacks since July, the most recent of which occurred on Feb. 3.
Iran is a major backer of Hezbollah. Both are allies with Syrian President Assad.