Forty-five opposition rebels were killed Thursday in the old city of Homs, the head of the Britain-based Syrian Observatory for Human Rights Ram Abdel Rahman told dpa.
Syrian forces loyal to president Bashar al-Assad attacked the city that has been under siege.
"Those rebels were killed in the area of al Matahen between Wednesday and Thursday as they were launching an attack to break a one-year siege by the regime on areas inside Homs," he said.
Syria's state News Agency confirmed the report but gave the number of dead as 37, who were killed in an ambush on the outskirts of the city.