Rival sectarian factions clashed in Lebanon's northern city of Tripoli on Saturday for a second consecutive day and medical sources said the death toll from the fighting rose to eight.

Gunmen exchanged heavy machinegun and grenade fire from Sunni and Alawite districts until dawn in the city where at least 21 people have been killed in the past two months by sectarian fighting linked to Lebanon's political turbulence.

The latest round of fighting in the predominantly Sunni city had wounded at least 65 people, the medical sources said. Residents have fled, many taking refuge in schools.

The interior minister promised firm action to halt the latest clashes. The dead included a woman, a boy and a man who was struck by a rocket-propelled grenade while driving his taxi.

Observers have linked bouts of violence in Tripoli since late June to lingering disputes between the Sunni-led parliamentary majority bloc and a rival alliance led by Shi'ite Hezbollah, which is close to Alawite groups in the north.

The sides' protracted political conflict was largely resolved in May by a Qatari-mediated deal. But disputes have continued. The rivals are now at odds over the policy statement of a national unity government which was finally formed on July 11 after weeks of wrangling over portfolios.

Language in the policy statement regarding Hezbollah's guerrilla army is the main area of disagreement.

Hezbollah, which is backed by Syria and Iran, used its arsenal in May to briefly seize Beirut and rout supporters of the anti-Damascus majority bloc.

The move helped Hezbollah impose the opposition's terms for a settlement with rivals including Sunni politician Saad al-Hariri - a strong opponent of Syrian influence in Lebanon who has wide influence in Tripoli.

The Alawite faith is a small offshoot of Shi'ite Islam and its adherents are mostly based in Syria which is ruled by President Bashar al-Assad, himself an Alawite.

Their numbers are small in Lebanon but they gained some political influence during an era of Syrian dominance that came to an end in 2005 after international pressure forced Damascus to withdraw troops from the country.