Fighting in the Lebanese port of Tripoli between supporters and opponents of the regime in neighbouring Syria killed nine people on Thursday, as a fifth day of violence spread to previously quiet neighbourhoods, a security source said.
"Very violent fighting took place last night until 5:00 am (0200 GMT) that killed six people and wounded 40. The clashes and shelling affected several areas of the city, including the centre," the source told AFP.
"On Thursday evening, snipers killed three people, one on Qobbah and two in Jabal Mohsen.
Violence has broken out repeatedly in Tripoli since the beginning of Syria's uprising, pitting residents of the Sunni Bab el-Tebbaneh district against those from the neighbouring Alawite area of Jabal Mohsen.
But since Sunday, shelling and clashes have spread to other mostly Sunni areas of the northern city of 500,000 inhabitants, killing 20 people including two soldiers and wounding 150 others.
An AFP correspondent reported only light traffic on Thursday, but said people were out and about and all the shops in the city centre were open for business.
However, many businesses were closed in Bab el-Tebbaneh and Jabal Mohsen, and most schools also did not open.
Troops have been deployed across the city since the outbreak, but this has failed to halt the fighting.
The latest violence began as the regime of Syrian President Bashar al-Assad launched a withering assault on the rebel stronghold of Qusayr, near the border with Lebanon.
Lebanese Shiite militant group Hezbollah has been sending fighters across the border to help Syrian regime forces attack Qusayr.
And on Thursday, a Lebanese source close to Hezbollah told AFP that 75 of the group's combatants have been killed in Syria in eight months.
The Britain-based Syrian Observatory for Human Rights gave a higher toll, saying that 104 Hezbollah fighters had been killed in Syria since last autumn, 46 of them in Qusayr in the past five days.
Amin al-Qabbut, mukhtar (municipal official) of the Sunni Al-Qobba area, said areas of Tripoli last attacked during the Syrian army's bombardment of the northern city in 1985 were being shelled again.
"This war is the continuation of the 1985 war that Syria waged against us," Qabbut said.
In 1985, during Lebanon's civil war, the Syrian army clashed with Sunni groups in Tripoli, and bombarded areas of the city.
"The political tool used to wage the war is the same, it is the Arab Democratic Party," Qabbut said, referring to the party linked to Tripoli's Alawite community.
The ADP has, in return, accused Sunni groups of starting the fighting.
The Sunni-majority port has been the scene of intense clashes between Sunni supporters of the anti-Syrian opposition and Alawite Muslims loyal to a Hezbollah-led alliance backed by Iran and Syria.
Assad, who is fighting a bloody uprising against his regime, is from the Alawite community, an offshoot of Shiite Islam.
The revolt in Syria has exacerbated tensions in Lebanon, which lived under three decades of Syrian hegemony and remains deeply divided between supporters and opponents of Damascus.