A passerby from the Sunni district of Bab al-Tebbaneh was wounded in the crossfire between fighters from his area and the neighbouring largely Alawite area of Jabal Mohsen, the official said on condition of anonymity.

Another person was wounded by sniper fire on Friday morning, the official added.

Stores in the area did not open on Friday because of the unrest, and an AFP correspondent said many people were fleeing their homes as sporadic gunfire was heard.

Three grenades also exploded overnight on Thursday in Tripoli despite a reinforced army presence aimed at restoring calm.

After the overnight incidents, gunmen from both sides were reported in the streets for the first time since the military deployed in full force in mid-July, pledging a tough response to any breach of security.

Repeated clashes between the two areas have left 14 people killed and more than 100 wounded since June.

Bab al-Tebbaneh is a stronghold of the anti-Syrian parliamentary majority while the inhabitants of Jabal Mohsen are mainly supporters of the Shiite Hezbollah-led opposition.

Alawites are a secretive offshoot of Shiite Islam who revere Imam Ali, the cousin and son-in-law of the Prophet Mohammed.

© 2008 Agence France-Presse