Lebanese militant movement Hezbollah has used weaponised drones against the Islamic State group across the border in war-ravaged Syria, its media arm said on Monday.
A source on the ground told AFP it was the first time that Hezbollah had deployed weaponised drones against IS in Syria, where the Shiite movement is fighting to bolster President Bashar al-Assad's forces.
"The armed drones of the Resistance (Hezbollah) targeted Daesh positions and fortifications in western Qalamun," Hezbollah's War Media channel said, using the Arabic acronym for IS.
On Saturday, Hezbollah said it had launched an operation against IS in a hilly region known as western Qalamun, near Syria's border with Lebanon.
Lebanon's army announced a simultaneous offensive on the Lebanese side of the frontier, and has already recaptured two-thirds of the area.
A source on the ground told AFP on Monday that "this is the first time Hezbollah has used weaponised drones in a clash with IS".
The group had deployed such drones in previous clashes with other jihadists and rebels, "but now we are unleashing a barrage of bombs", the source said.
Security along Lebanon's unmarked eastern border with Syria has long been a concern.
Last month, Hezbollah waged a six-day assault against Al-Qaeda's former affiliate in the border region, which ended in the evacuation of the jihadists and thousands of civilians.
The current offensive targets remaining territory further north along the frontier where IS militants have entrenched themselves.
The Lebanese army has denied any coordination with Hezbollah or the Syrian army on the ongoing assault.
IS itself has used weaponised drones to defend territory it holds in Iraq and Syria from US-backed offensives.
The group claimed twin attacks in Spain on Friday that left 15 people dead.