Fourteen people were killed in fierce clashes in north Lebanon on Saturday between supporters of the Western-backed government and the opposition, a security official told AFP.
"The headquarters of the Syrian Social National Party (SSNP) in Halba fell to the Future Movement forces," the official said, adding that seven people were found dead inside.
The toll from the fighting in the north has now risen to 14 from five reported dead earlier in the day, the official said.
He told AFP earlier that civilians were among the casualties.
The fighting in the town of Halba in the Akkar region pitted a pro-Syrian party allied with the Hezbollah-led opposition against members of the Western-backed ruling bloc, the official said.
Tripoli, the main city in northern Lebanon, was also the scene of violence between supporters of the government and the opposition.
"The offices of the Syrian Social Nationalist Party as well as Hezbollah's offices in the area have been torched and damaged by supporters of the Future Movement," the official said.
He said the Lebanese flag and pictures of slain former premier Rafiq Hariri were hung outside the offices. The billionaire was assassinated in 2005 in a bombing widely blamed on Syria although Damascus has denied any involvement.
Control of the Tripoli office of Christian opposition leader Michel Aoun was handed over to the army, the official added.
In another incident, seven Syrian labourers from Aleppo and their driver from south Lebanon were wounded by gunmen who set up a checkpoint on the Minya highway north of Tripoli, the security official said.
Four days of fighting between mainly Sunni supporters of the government and Shiite supporters of the opposition have left more than 30 dead, with west Beirut falling under opposition control and the offices of the Sunni Future Movement being turned over to the army in many areas.