Fighters from hardline Syrian militant groups killed nine regime fighters near a planned buffer zone around the country's last major rebel bastion on Friday, in an attack that adds to fears over a ceasefire deal for the region.
The September deal between government ally Russia and opposition backer Turkey aimed to set up a demilitarised zone around the north-western region of Idlib to protect it from a regime assault and prevent a humanitarian catastrophe in the heavily populated province.
But its implementation has been stalled since hardline militants who hold about 70 per cent of the planned buffer area failed to withdraw by mid-October, and sporadic clashes have rocked the area since.
Early on Friday, the militants attacked government forces in the north-west of Hama province near the planned buffer zone, the Britain-based Syrian Observatory for Human Rights said.
"Nine regime fighters and five assailants were killed" in the attack, causing government forces to respond with artillery fire, Observatory head Rami Abdel Rahman said.
The attackers included the Al Qaeda-linked Hurras Al Deen group, which has publicly rejected the Russian-Turkish deal, he said.
The lion's share of Idlib is held by Hayat Tahrir Al Sham, an alliance led by Al Qaeda's former Syrian affiliate.
Under the September 17 deal, all fighters in the zone were supposed to withdraw their heavy weapons and hardline militants including HTS and Hurras Al Deen were supposed to leave.
On Thursday, Russian spokeswoman Maria Zakharova criticised "sporadic clashes", as well as "provocations" by HTS in north-western Syria.
On November 8, the 20 fighters of the Jaysh Al Izza rebel group were killed in attack they claim was carried out by Iran-backed pro-regime militias and supported by Russia. A retaliatory attack by HTS killed eight regime fighters.
The clashes have led to an escalation in tensions that threaten the ceasefire agreement.
Late last month, Syria's Foreign Minister Walid Muallem expressed dissatisfaction with the implementation of the Idlib deal, and criticised Turkey for shortcomings.
He said heavy weapons had not been withdrawn and accused Turkey of not wanting to "respect its obligations".
Syria's war has killed more than 360,000 people since it erupted in 2011 with the brutal repression of anti-government protests.
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