Syrian activists say nearly 500 people, including 85 civilians, have been killed in fighting among Syrian rebels and hardline Islamist State of Iraq and the Levant, or ISIL.
The Syrian Observatory for Human Rights said Friday that 482 people have been killed in the seven days during intense clashes in Aleppo, Idlib, and Raqqah provinces. Of the 85 civilians, it said 21 were executed by ISIL fighters and the rest were killed in crossfire.
The Observatory said 240 combatants from Islamist and non-Islamist rebel battalions were killed in violent clashes, car bombings, or other attacks on vehicles in Aleppo, Raqqa, Hama, and Idlib. It said more than 20 people were executed by the ISIL in Aleppo.
The group also said 157 ISIL fighters died in the fighting, including 47 who were executed by rebels.
Meanwhile, the Syrian government's SANA news agency said Friday the army killed 37 rebels, who it refers to as terrorists, as they tried to leave an area north of the central city of Homs, which is surrounded by the army.
Neither SANA nor the Britain-based Observatory gave figures on government casualties.
Forces loyal to Syrian President Bashar al-Assad have for months surrounded Homs - Syria's third-largest city - which was a center of the opposition uprising against his rule.
Assad loyalists are fighting a fractured opposition force, which has in recent days seen increased clashes between its Islamist and Western-backed elements.
Syrian rebel fighters hold their weapons as they walk along a street in Aleppo's Salaheddine neighborhood, Jan. 10, 2014.
A Free Syrian Army fighter looks on as he holds the Syrian opposition flag during a protest against Syria's president and fighters from the Islamic State in Iraq and the Levant in Aleppo's Salaheddine neighborhood, Jan. 10, 2014.
A boy holds bread as he walks in front of the Syrian opposition flag during a protest against Syria's president and Islamic State in Iraq and the Levant in Aleppo's Salaheddine neighborhood, Jan. 10, 2014.
Bystanders look on as crews begin clearing the wreckage of a car bomb that exploded near a school in Al-Kafat, Syria, Jan. 9, 2014.
The remains of a car destroyed by a suicide bomb near the front of a damaged building in Al-Kafat, Jan. 9, 2014.
People survey the damage to a building destroyed by a suicide car bomb in Al-Kafat, Syria, Jan. 9, 2014.
Damaged buildings line a deserted street in the besieged area of Homs, Jan. 9, 2014.
Free Syrian Army fighters are deployed in Kadi Askar in Aleppo after they claimed that they seized it from the Islamic State in Iraq and the Levant, Jan. 7, 2014.
Free Syrian Army fighters prepare to launch a mortar towards fighters from the Islamic State in Iraq and the Levant from a street in the Kadi Askar neighborhood of Aleppo, Jan. 7, 2014.
Men help a wounded boy who survived what activists say was an airstrike by forces loyal to Syrian President Bashar al-Assad in the Duma neighborhood of Damascus, Jan. 7, 2014.