At least three people were killed in fighting between rival religious sects in Lebanon's second city on Wednesday, medical and security sources said, as violence from Syria spills over into the small Mediterranean country.

The dead in the coastal city of Tripoli included an 11-year-old boy, as well as two men, the sources said.

The long-running rivalry between Tripoli's Sunni Muslims and members of the Alawite sect, an offshoot of Shi'ite Islam, has been worsened by Syria's three-year-old conflict.

The civil war has become increasingly sectarian as mostly Sunni rebels - who represent the majority in Syria - battle President Bashar al-Assad, an Alawite.

That has in turn exacerbated tensions in Lebanon, which is home to Sunnis, Shi'ites, Christians and a number of smaller sects, and is still recovering from its own 1975-90 civil war.

At least 27 people have been killed in fighting in Tripoli over roughly the last two weeks, including one Lebanese soldier.

(Reporting by Nazih Siddiq; Writing by Alexander Dziadosz; Editing by Sonya Hepinstall)

(Reuters) -