BEIRUT: The Syrian army and its allies aim to strike insurgents to the south and west of Aleppo after encircling the rebel-held half of the city, blocking rebels from sending reinforcements from their stronghold in Idlib, a Syrian military source said Monday.

Backed by Russian airstrikes, the Syrian army and allied militia blocked off the last route into the insurgent-held areas of eastern Aleppo Sunday, a long-held goal in the five-year-long conflict.

"The army wants to complete and expand its control around the city in general," the source said. "All positions where terrorists are located to the west of Aleppo and south of it are being attacked because this area is a priority for the the army, given that Idlib is the human resources store (for the rebels)."

The army and its allies were working to widen their control near a complex of military colleges captured from the rebels Sunday, the source added.

"Now the army's belt of control is being widened in the area of the colleges and nearby areas to the south and west," a Syrian military source told Reuters. "This expansion is very necessary because this is the direction that secures passage for the terrorists from the Idlib countryside."