The death toll in Lebanon's northern city of Tripoli reached 25 on Saturday in the seventh straight day of clashes between factions supporting opposing sides in Syria's two-year civil war, security sources said.
Residents heard sounds of rocket-propelled grenades and sniper fire throughout the night and into Saturday morning in one of the most violent bouts of fighting so far in the city.
Two people were killed on Saturday, according to medical sources. Security sources said 25 had died in the clashes in the past week.
The coastal city's Sunni Muslim majority supports the Sunni-led revolt in Syria, where Sunnis are also a majority. But an Alawite enclave in Tripoli supports Syrian President Bashar al-Assad, from the same sect, an offshoot of Shi'ite Islam.
Assad has garnered support from many in minority groups like the Alawites. Fear of Islamist radicals who are have joined rebel ranks in the fight against Assad's government has mobilised many in minority groups, including Alawites beyond Syria's borders.
The launch of an offensive by Assad against the strategic Syrian town of Qusair, close to the Lebanese border, has added to the risks of the conflict spreading into Lebanon.
The Shi'ite militant group Hezbollah has helped Assad's forces in the assault there, inflaming Sunni-Shi'ite regional tensions that are already on the rise.
Each side accuses the other of using Tripoli as a base to gather weapons and supplies headed into Syria and cities like Qusair.
Residents said the recent spate of fighting in Tripoli has been the fiercest so far, including the use of heavy weapons such as advanced machine guns and mortar bombs.
More than 250 people have been wounded in the fighting, medics say.