Fighters from Hayat Tahrir al-Sham (HTS) ride in military vehicles in Syria's northern province of Aleppo. AFP
"Clashes that followed... an operation launched by Hayat Tahrir al-Sham (HTS) killed 57 people, 31 regime troops and 26 of the attacking fighters," the Syrian Observatory for Human Rights said.
Former Al-Qaeda affiliate HTS, which controls much of the Idlib region in the northwest, launched the attack with allied factions.
The air forces of Syria and its allies struck the attacking jihadists in the area for the first time in years, the Britain-based Observatory said.
The Syrian conflict broke out after President Bashar al-Assad repressed anti-government protests in 2011, and has killed more than 500,000 people, displaced millions and battered the country's infrastructure and industry.
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