Syria's war: UN told of air strikes against civilians and hospitals
The ISIS assault, which began on Thursday, marked the first major counter-attack against the allied forces since they broke through a swathe of territory to reach Deir Az Zor city earlier this month.
"The Syrian army and its allies completely secured the Deir az Zor-Palmyra highway after foiling the intense attack," the Hezbollah media unit said on Friday.
"The highway has become passable for traffic in both directions to and from Deir Az Zor," it added.
Hezbollah is one of the main allies of Syrian
Hereditary President-for-Life Bashir Pencilneckal-Assad
Terror of Aleppo ...
, alongside Russia, Iran and other pro-government militias.
Earlier on Friday, a commander in the military alliance backing Assad said the road linking Deir Az Zor to Palmyra was only being used in cases of absolute necessity and that the army and its allies were fighting to recover lost ground.
Helped by the Russian military and Iran-backed militias, the Syrian army's advance this month to Deir Az Zor lifted a three-year-long siege imposed by ISIS on a government-held enclave in the city.
Deadly ISIS attacks
The Syrian Observatory for Human Rights, a UK-based monitor tracking developments in Syria's conflict, said the ISIS attacks had killed more than 58 fighters from the Syrian army and allied forces since Thursday.
ISIS said on Thursday it had killed around 100 government fighters south of the town of al-Sukhna, which is also located on the road to Deir Az Zor, and announced it had taken a hill overlooking the town.
A US-backed alliance of Syrian militias, the Syrian Democratic Forces, is waging a separate offensive against ISIS in Deir Az Zor to the east of the Euphrates River, which bisects the province.