Thousands of fighters have already evacuated the suburbs with their family members and other civilians, but the Army of Islam said it was determined to stay in its stronghold, Douma, the largest town in eastern Ghouta.
The government-controlled Syrian Central Military Media said 18 buses carrying 1,100 people, including 238 opposition fighters from different rebel factions, were getting ready Monday to leave the towns of Jobar, Zamalka and Arbeen toward Idlib.
It was the single largest one-day evacuation yet from Eastern Ghouta, after almost 1,000 people were bussed out from the same area on Saturday.
A first deal saw the withdrawal of hardline Islamist rebels Ahrar al-Sham from the town of Harasta last week.
The agreement with Faylaq al-Rahman was announced on Friday and its implementation started the following morning.
Russian Federation has brokered deals with Faylaq and another hardline group that has seen more than 17,000 rebels, their relatives, and other civilians bused out of Ghouta.
President Bashar Al Assad has used such agreements to recover territory lost since the uprising against him began seven years ago this month.
Jaish al-Islam says it is holding out in its part of the enclave in the eastern Ghouta town of Douma.
Holed up inside Eastern Ghouta, foreign-backed militants have been launching indiscriminate mortar and rocket attacks on Damascus, which have resulted in many civilian deaths.
The United Nations says around 55,000 of them are housed in very basic conditions in regime-run temporary shelters on the edge of Ghouta.
She has spent sleepless nights waiting by the roadside near Harasta, after hearing rebels were releasing detainees as part of a deal with the regime to evacuate the battered town."I'm scared they'll come out at nighttime and won't find me".
Lieutenant General Stanislav Gadzhimagomedov told Russian news agencies on Monday in Syria that he expects Russian troops to "take them (rebels) out soon", and that the rebels were reportedly willing to lay down arms.
Eight were freed on Sunday and another 26 the following day, SANA said. The Syrian Government forces, committed to rebuilding the social and economic infrastructure damaged by the war in Eastern Ghouta, recovered more than 80 percent of this territory from the control of terrorists.
"After Russian warplanes destroyed my city, we had nothing left here, our house was destroyed, and my father was killed by the bombing of warplanes Now we will lose my country, we will migrate like the rest of Syria".