BEIRUT: Militants gained ground on Friday from forces in Syria's last major opposition bastion after four days of clashes that have killed more than 100 fighters, a war monitor said.
Hayat Tahrir al-Sham, a militant-led alliance, seized more than 20 towns and villages from rival forces in the northern province of Aleppo, the Syrian Observatory for Human Rights said.
"HTS was able to take control of areas previously held by Nureddine al-Zinki in the west of the Aleppo countryside," the Britain-based monitor said.
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Those areas lie in the northeast of Syria's last major opposition bastion, which includes a large part of Idlib province as well as adjacent parts of Aleppo and Hama provinces.
The clashes broke out after HTS, which is led by Syria's former Al-Qaeda affiliate, on Monday accused Nureddine al-Zinki of killing five of its fighters.
Fighting flared on Tuesday in the northern province of Aleppo before expanding to the neighbouring provinces of Idlib and Hama in the following days.
Two HTS fighters and 14 from opposition forces were killed in the fighting on Friday, the Observatory said.
Airstrikes by government ally Russia hit the west of Aleppo province late on Friday, killing two civilians in the town of Darat Izza, the observatory added.
They were the first such raids on the west of Aleppo province since a deal between Moscow and opposition backer Ankara to stave off a massive regime offensive on the wider Idlib region in September.
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That brings the overall death toll to 61 HTS fighters, 58 from opposition forces, and 10 civilians in four days, it said.
Over the past two years, HTS has regularly fought a rival alliance of opposition called the National Liberation Front, which includes Nureddine al-Zinki, for territory in and around Idlib province.
Sparked by the brutal repression of anti-government protests in 2011, Syria's civil war has killed more than 360,000 people and displaced millions.
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