(Adds rocket attacks)
By Nazih Siddiq
TRIPOLI, Lebanon, March 15 (Reuters) - The death toll from three days of fighting between members of two Muslim sects in the northern Lebanese city of Tripoli rose to 10 on Saturday, security and medical sources said, in violence stoked by the civil war in neighbouring Syria.
One person was killed by a sniper and four more died on Saturday from injuries sustained earlier in the week during clashes between Sunni Muslims and members of the Shi'ite-derived Alawite sect in Lebanon's second city.
The fighting broke out on Thursday after gunmen fatally shot a Sunni man who had Alawite family members and lived in a mostly Alawite area of the city. A 10-year-old girl died in the resulting clashes and three others died from their wounds the next day.
More than 50 people, including at least eight Lebanese soldiers, were wounded in clashes in which snipers and rocket-propelled grenades were used.
The fighting had subsided by Saturday following intervention by the army, but snipers from both sides were still operating around Syria Street, which separates the Alawite enclave of Jabal Mohsen from the Sunni district of Bab al-Tabbaneh.
The sources said most of those killed were civilians and that they were all Sunni Muslims, though one of them had lived in the Alawite neighbourhood.
The long-standing rivalry between Tripoli's Alawites and Sunnis has worsened because of sectarian tensions in Syria, where the three-year-old conflict has killed more than 140,000 people.
Lebanese Sunnis largely support the Sunni-led uprising against President Bashar al-Assad, who tends to enjoy the backing of his fellow Alawites.
The periodic clashes in the coastal city have been fought with increasingly sophisticated weaponry, as rocket-propelled grenade launchers have been used alongside lighter weapons like assault rifles.
In another incident of spillover from the Syrian war, several rockets hit towns near Baalbek, a heavily Shi'ite area 55 km (35 miles) southeast of Tripoli and just a few kilometers from the Syrian border.
Lebanon's National News Agency said one man was killed in the village of Nabi Osmane, and two people were wounded in the town of Labwa.
A security source told Reuters the rockets came from across the border, where Syrian government forces advanced on the town of Yabroud, the last rebel bastion on the mountainous frontier. (Additional reporting by Stephen Kalin in Beirut; Writing by Stephen Kalin; Editing by Raissa Kasolowsky/Rosalind Russell)