Lebanon is home to more than a million refugees fleeing the six-year conflict in neighbouring Syria, but Lebanese ministers say they must go home to safe territory as soon as possible.
The refugees returned today under a deal negotiated by Syrian rebels in the camps and Lebanese militant group Hezbollah, which is fighting in Syria on behalf of President Bashar al-Assad's government.
A security source told AFP that the convoy carried between 250 to 300 refugees.
It was the second organised return for displaced families in Arsal to Assal al-Ward, after Lebanon's army announced a similar operation in early June.
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Assal al-Ward, about 40 kilometres southeast of Arsal, has been relatively stable since it was recaptured from rebels by Syrian regime forces and Hezbollah.
The UN refugee agency in Lebanon and the Syrian Arab Red Crescent both told AFP they were not involved in the operations.
An AFP correspondent saw refugees aboard 24 vehicles, including cars, tractors, and pick-up trucks, crossing the rocky no-man's land that forms the border between Lebanon and Syria.
Once in Syria, the group was met by local government officials and members of Hezbollah, AFP's correspondent said.
A local source from Hezbollah said the operation took place "after negotiations between Hezbollah and armed men in the camp."
The atmosphere in Arsal has been particularly tense after army raids on two refugee settlements in the area on June 30.
The raids were met with suicide attacks and grenades, and security forces subsequently arrested dozens of people from the camps.
It comes nearly three years after deadly clashes around Arsal between the army and jihadists who kidnapped 30 Lebanese security forces.
Sixteen were released in December 2015 in exchange for Islamist prisoners held in Lebanese jails, while four were executed and a fifth died of wounds suffered during the fighting.
Nine remain held by jihadists.