BEIRUT: Lebanon's army said on Friday it was stepping up security at religious sites and other public places over the Muslim Eid al-Fitr holiday after a spate of kidnappings in Beirut and protests which blocked the airport road.

"Army units started taking exceptional security measures in the vicinity of religious places, main roads, shopping areas and tourist attractions," the army said in a statement.

A Lebanese Shi'ite clan kidnapped 20 Syrians and a Turkish businessman this week, saying it was holding them to secure the release of a relative captured by Syrian rebels in Damascus.

Sectarian tensions are already running high in Lebanon over the uprising in neighbouring Syria, where mainly Sunni Muslim rebels are seeking to overthrow President Bashar al-Assad, whose Alawite sect is an offshoot of Shi'ite Islam.

Eleven Shi'ite Lebanese men have been held in northern Syria by Syrian rebels for more than three months. Families of the captives burned tyres and blocked the Beirut airport road on Wednesday night after reports that some of their relatives had been wounded in a government air strike.