Syrian regime air strikes killed more than 30 people Saturday in the Latakia province, bastion of the ruling Assad clan, and the northern city of Raqa, a monitory group said.
Seven children were among at least 13 civilians killed in an air raid on Raqa, the only provincial capital in rebel hands, according to the Syrian Observatory for Human Rights.
It said the raid was apparently aimed at positions of the jihadist Islamic State of Iraq and the Levant (ISIS) which largely controls the city.
ISIS has been the dominant force in the city since its capture by rebels in March. Residents have held several protests against the policies of ISIS which follows an extremist line of Islam, according to the Observatory.
An Italian Jesuit priest and activist, Paolo Dall'Oglio, who hoped to negotiate with ISIS in Raqa, went missing in the city at the start of August.
In the coastal Latakia province of northwest Syria, at least 20 people were killed in several air strikes on the Sunni rebel town of Salma in the Jabal al-Akrad area, the Observatory said.
At least six of those killed were Syrian rebel fighters, while four were foreign volunteers, said Rami Abdel Rahman, who heads the Observatory.
Latakia province is a stronghold of the Alawite minority of President Bashar al-Assad, apart from rebel-held pockets.
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Islamist rebel forces have captured about 10 Alawite villages in the Jabal al-Akrad, a mountainous area of the province. The army has hit back, sparking fierce fighting that has left dozens dead on both sides, according to the Observatory.
In their operation, the rebels have kidnapped a leading Alawite cleric, Sheikh Badreddine Ghazal, said the Observatory, which relies on a network of activists on the ground and medics for its information.
In Damascus, a car bomb ripped through the Shaghur district of the capital late Saturday, wounding several people, three of them children, said the Observatory.
In Aleppo province, further east, government troops stormed a village overnight, killing 12 people, the Observatory said.
Al-Nusra Front jihadists and other rebel fighters in the eastern city of Deir Ezzor seized control of the offices of Syria's ruling Baath party in the Howeika district, sparking regime bombardment, the Observatory said.
ISIS fighters have clashed for the past month with Kurdish militia forces in the Raqa region, triggering a warning on Saturday from Iraqi Kurdish leader Massud Barzani of a cross-border intervention to protect fellow Kurds.
Syria's Kurds, marginalised by Damascus for decades, have walked a fine line since the conflict began, trying to avoid antagonising loyalist forces or rebels who have fighting since March 2011 to overthrow Assad.
More than 100,000 have been killed in the past 29 months of conflict.