Among the 56 killed on Thursday were 16 protesters shot dead by soldiers in Homs, 140 km (90 miles) north of Damascus, where troops have tried to crush protests as well as an armed insurgency, the Syrian Observatory for Human Rights said.
Fourteen others were killed in house-to-house raids and in protests in Damascus suburbs, the southern province of Deraa and the northwestern province of Idlib near Turkey.
Twenty six soldiers were killed in ambushes, activists said, 25 near Maarat al-Numaan, a town 70 km south of Aleppo, and in the nearby city of Khan Sheikhoun, said the British-based Observatory, headed by dissident Rami Abdelrahman. Another soldier was killed in the eastern province of Deir al-Zor.
Both towns are in Idlib, where an increasing number of army deserters and insurgents are taking refuge, helped by the region's rugged terrain and proximity to Turkey, activists say.
An activist in the eastern Damascus suburb of Harasta, who gave his name as Assem, said three deserters were killed after they abandoned military units which fired live ammunition at a demonstration of 1,500-2,000 people in the al-Zar neighborhood.
"Security police could not put down the demonstration. The eight soldiers defected when Republican Guards and the Fourth Armored Division were sent in," he said.