"The people want the fall of the regime," chanted the group gathered on the Lebanese side of Al-Boqayah, an illegal crossing on the Syrian-Lebanese border, as Lebanese troops looked on.
"We don't love you, Bashar," and "Tall Kalakh, have no fear, we are with you," they shouted as an AFP correspondent said.
Most of the protesters hailed from the Syrian towns of Tall Kalakh and Arida near the border.
Hundreds of Syrians, mainly Sunni Muslims, this month have poured into Wadi Khaled on foot from villages near the border, bringing with them mattresses and other basic provisions.
While they declined to give their names for fear of reprisals, many of those gathered at Al-Boqayah on Monday said that Syrian security forces had cracked down on their home towns, which the army had placed under siege.
They recounted how those who made it out had crept through orchards overnight.
"The Syrian army is targeting our homes from their tanks and with missiles," said one Tall Kalakh resident who fled his hometown overnight.
"The wounded lie with the corpses in our streets, and no one dares to move them to hospital," he told AFP.
Another young man said Alawite Muslims in villages around Tall Kalakh had begun to take up arms against Sunnis, who form the majority of Syria's population of some 20 million.
An AFP correspondent in Wadi Khaled said intermittent gunfire could be heard coming from the Syrian side of the border on Monday.
For two months, Syria has been rocked by increasingly deadly demonstrations against close to five decades of rule by the Alawite-controlled Baath party.
More than 850 people, including women and children, have been killed and at least 8,000 arrested as security forces cracked down on the protest movements, according to rights groups.
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