Fighters from Jaish al Islam are reported to have reached an agreement to allow them to leave Douma, the last remaining suburb under rebel control in the suburb on the outskirts of Damascus.
Rebels from a different group, Failaq al Rahman, finished pulling out of eastern Ghouta on Sunday.
Thousands of fighters have been leaving the area during the last week after the Syrian government said they could be conscripted by the regime or travel to rebel-held areas in the north of the country.
They began pulling out after reaching an agreement to allow them to go to Idlib province.
Tens of thousands of civilians have also been leavingthe enclave.
The UK-based Syrian Observatory for Human Rights says regime forces control of 94% of eastern Ghouta, with just Douma remaining in rebel hands.
Failaq al Rahman fighters were forced into Douma by a recent government offensive which broke through rebel lines and cut eastern Ghouta into three parts, according to local media activist Ahmad Khansour.
On Sunday, Failaq al Rahman fighters in Douma followed their comrades trapped in the other two Ghouta pockets to Idlib in buses laid on by the Syrian government, SANA news agency reported.
Last week, the Syrian government said it regained control of several towns and villages that had been under siege for years.
Many had suffered weeks of heavy bombardment with hundreds of civilians said to have been killed.
Tens of thousands more civilians trapped in eastern Ghouta await relief.
Douma’s fall will represent the rebels’ worst defeat since 2016, driving them from their last big stronghold near the capital.
State television and Syrian newspapers said that the deal with Jaish al Islam would involve the group handing over heavy and mid-sized weapons and acknowledge Syrian government sovereignty over Douma.
Jaish al Islam, the last remaining rebels in Douma, had no immediate comment on the reports.
News on the deal was also reported by a media unit run by Hezbollah.
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Bashar al Assad’s government lost control of Douma in the early phase of Syria’s civil war, which started in spring 2011.
A five-week Syrian government offensive, backed by its Russian allies, has killed at least 1,600 civilians and displaced tens of thousands more, according to the Syrian Observatory for Human Rights.