The Britain-based Observatory said those killed on Tuesday included four civilians and one rebel in the northern city of Aleppo, four civilians in Damascus, a rebel in Deir Ezzor and four Syrian army soldiers in Idlib.

The opposition Syrian National Council Tuesday also reported at least eight other people killed as regime forces put down a mutiny in an Aleppo prison during the night.

It said the deaths occurred when regime forces fired bullets and tear gas at protesting prisoners.

In an updated toll, the Observatory said 116 people were killed across Syria on Monday, including 64 civilians, 17 rebel fighters and 35 Syrian troops.

Rebels forces battled regime soldiers in several neighbourhoods of Syria's second city Aleppo, as the army fought to retake districts of Damascus from the rebels, it said.