Syrian military helicopters launched three raids in areas inside Lebanon close to the border town of Arsal on Monday morning, witnesses and Lebanon's official news agency said.
Helicopters carried out the raids in the largely unpopulated mountainous areas on the outskirts of Arsal near the Syrian border, witnesses told AFP.
It was unclear if there were any casualties in the raids, which Lebanon's National News Agency said hit the areas of Khirbet Yunin and Wadi Ajram.
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Syrian war planes and helicopters regularly carry out air strikes and rocket attacks in the border area inside Lebanese territory.
In December, the Lebanese army used its air defence systems against Syrian helicopters after one such attack in the area around Arsal.
That was believed to be the first time the Lebanese army had responded to a raid, though it had previously threatened to do so.
Arsal's residents support the revolt against Syrian President Bashar al-Assad and the town is hosting tens of thousands of refugees, including a recent influx driven out by a new offensive just across the border in the Qalamun region.
The area around Arsal has long been home to smuggling routes that are used by opposition forces to move fighters and weapons back and forth between Lebanon and Syria.