Artillery and rocket shelling by the Syrian army on the positions of Jaish al-Fateh left the rebels in a state of "confusion.
According to Al-Alam report, many rebels were either killed or wounded by the shelling on al-Ramouseh, Musherfeh, and the Project 1070 areas in southwestern Aleppo.
Meanwhile, opposition activists said that a rebel commander was killed in the Project 1070 area during battles with government forces.
Yousef Zaoua, the general military commander of the Jaish Al-Mujahideen terrorist faction, was killed today by the Syrian Army in the intense firefights of southwest Aleppo.
The Syrian army carried out a preemptive strike against a rebel position in the countryside of Aleppo on Wednesday evening, inflicting hefty losses among the opposition militants.
The military forces targeted gatherings of the rebels' Jaish al-Fateh group in the Project 1070 area, one of several areas that have recently fallen to Jaish al-Fateh, in the southern countryside of Aleppo.
The source noted that the rebels were preparing to unleash an all-out offensive in Aleppo.
According to SANA the Syrian and Russian air forces dealt "decisive strikes" on the positions of Jaish al-Fateh in southern Aleppo killing large numbers of them and destroying armored vehicles outfitted with machine guns.
The strikes destroyed four command centers, three booby-trapped vehicles and dozens of armored vehicles, SANA added.
It said the Russian and Syrian air forces had killed hundreds of terrorists a day earlier in Aleppo, isolating the battle areas from the rest of the province.
Jaish al-Fateh announced last Monday that the next phase of battles in Aleppo will be a wide-scale offensive to "liberate the entire city" from government forces.
Jaish al-Fateh, or the Army of Conquest, an alliance of several rebel factions, was reportedly formed in March 2015 under the supervision and coordination of Saudi cleric Abdullah al-Muhaysini.
Aleppo is strategic for all warring parties due to its key location beside the Turkish border and role as Syria's industrial capital.