Heavy clashes including shelling and gunfire raged in the Syrian city of Aleppo today after a truce deal meant to halt fighting between government forces and rebels stalled, the Syrian Observatory for Human Rights said.

"The clashes are violent and bombardment is very heavy ... it seems as though everything (the ceasefire) is finished," Rami Abdulrahman, director of the British-based monitoring group, said.

Rights groups yesterday reported a 'massacre' of civilians in areas just occupied by Syrian government forces.