President Bashar al-Assad's army has started an operation in the rebel-controlled city of Raidan. On Monday, the Syrian forces stormed the streets and villages in and around Bomar, as well as bombarded them with heavy shelling.
The Syrian Observatory for Human Rights said in the statement.
A minister of Assad government last week said that after the recovery of surrounding areas in Damascus, their next goal would be to restore rebel-regulated areas of the Midwestern Route.
Observers believe that rebels from the southern areas of Damascus will be allowed to leave because the areas will be controlled by government forces within Monday.
Islamic State (IS) and rebel groups have control over areas controlled by rebels south of Damascus. Since the rehabilitation of the Syrian army, the rebel-controlled areas began to recover.
Meanwhile, the Syrian state media said rebel groups in the area agreed to move to the northern part of the state of Idlib.