A key hospital in Syria's rebel-held Eastern Ghouta was put out of service on Tuesday, a medical group said, with a monitor blaming Russian air strikes.
Syrian government or Russian air strikes targeted US-backed Syrian militias in Deir al-Zor province at dawn on Saturday, a militia official told Reuters.
At least 46 people were killed in suspected Russian air strikes on several areas of Idlib province in northwest Syria on Sunday, the Syrian Observatory for Human Rights said.
Syrian and Russian warplanes have launched a wave of air strikes in northern Syria, killing dozens in areas held by a rebel alliance battling to take control of second city Aleppo.
At least 24 Islamic State group fighters and eight civilians were killed in air strikes Sunday on Syria's Raqqa, the de facto capital of IS, a monitor said.
Russian warplanes carried out intense air strikes on rebel strongholds in Syria on Friday hours before a ceasefire is due to come into force, the Syrian Observatory for Human Rights monitor said.
Thousands of Syrians were braving cold and rain at the Turkish border on Saturday after fleeing a Russian-backed regime assault on Aleppo in northern Syria that threatens a fresh humanitarian disaster.