Syrian helicopters fired rockets near a Lebanese border area whose residents back the rebellion against President Bashar al-Assad, a security official said, in the latest incident rasing new concerns of Syria-related escalation in Lebanon.

The late Friday raid was second such Syrian strike against the Sunni-majority border areas in less than a week.

"Syrian helicopters fired rockets at the Wadi Hmeid area near (the town of) Arsal. There were no casualties," the Lebanese official said on condition of anonymity.

The attack was the latest in a series related to the escalating war in Syria, in which Lebanese Shiite movement Hezbollah has become fully engaged.

On Wednesday, a Syrian helicopter strafed Arsal, the majority of whose residents are Sunni and support the anti-Assad revolt in Syria.

The latest raid comes soon after the Syrian town of Qusayr was captured by the regime army and Hezbollah fighters from the rebels after nearly three-weeks of fierce fighting.

Ever since the Syrian revolt erupted in March 2011, Arsal has become a key conduit for refugees and wounded people fleeing strife-torn Syria.

Security officials say the town has also served as a passageway for fighters and arms flowing into Syria.

Syria's civil war has exacerbated sectarian tensions in Lebanon, which is deeply divided between supporters and detractors of Assad's regime.

Syria dominated Lebanon politically and militarily for 30 years until 2005, and continues to exercise significant influence through its allies.

On Friday, the Lebanese army warned a plot was being hatched to embroil Lebanon in the Syrian war.