"An Israeli drone launched an attack targeting a military convoy... killing two members of the Military Operations Department" and one civilian, in southern Syria's Quneitra region, the Syrian Observatory for Human Rights said.

A medical source told AFP a local official from the Ghadir al-Bustan area was among the three killed in the strike.

"This is the first Israeli strike targeting the security forces of the new authorities," said Rami Abdel Rahman, who heads the British-based Observatory with a network of sources inside Syria.

Security forces had been conducting a sweep in the area to search for weapons in civilian homes, the Observatory said.

Israel has launched hundreds of strikes on targets belonging to Syria's now-defunct army since Islamist-led forces ousted President Bashar al-Assad on December 8, destroying most of the military's arsenal, the Observatory has said.

The same day Assad was toppled, Israel also announced that its troops were crossing the armistice line and occupying a UN-patrolled buffer zone that has separated Israeli and Syrian forces on the strategic Golan Heights since 1974.

Israel seized much of the Golan Heights from Syria in a war in 1967, later annexing the territory in a move largely unrecognised by the international community.