BEIRUT -- Syria's partial ceasefire is unravelling, as fierce fighting between government forces and opposition fighters, including members of the al-Qaida affiliated Nusra Front, erupted Saturday outside the country's second largest city of Aleppo.
At least 25 pro-government fighters died in clashes south of Aleppo, where the Nusra Front and rebel militias captured a hill overlooking a major highway, a Britain-based monitoring group told The Associated Press.
The Syrian Observatory for Human Rights said fighting continued throughout the day Saturday close to the village of Tel al-Ais, which overlooks the main road connecting Aleppo with the capital, Damascus.
The co-ordinated rebel and Nusra Front offensive follows weeks of air raids on opposition-held areas despite the partial ceasefire. The truce agreement, the first of its kind in Syria's five year war, excludes the Nusra Front and the Islamic State group.
On Thursday, a bombing carried out by government planes outside Damascus killed 33 civilians, the Syrian Observatory for Human Rights reported. Government airstrikes also targeted the public square in the opposition-held city of Maarat Nouman in the northern Idlib province Friday, where residents had protested against the Nusra Front presence in the town.
Several rebel factions boasted about battling government forces on social media, including groups nominally subscribing to the cease-fire.
The Islam Army, whose political co-ordinator heads the opposition delegation engaged in peace negotiations with the government in halting talks in Geneva, announced it had killed 20 soldiers in fighting outside Damascus Friday.
The Nusra Front boasted of the offensive on the Aleppo countryside on social media, posting videos showing mortars and tanks firing on what is said to be government positions. Syria's state news agency acknowledged fierce clashes in the area Friday.