Under the deal, all Jaish al Islam fighters will shift from the eastern Ghouta pocket to Jarablus "within 48 hours", regime-run SANA news agency reports, a day after an alleged chemical attack blamed on Assad regime killed over 40 people in Douma.
Syria's regime has reached an agreement for opposition fighters to leave their battered holdout of Douma for an opposition-held town in the country's north, regime media reported on Sunday.
The regime-run news agency SANA, citing a regime source, said the agreement would see the departure of all Jaish al Islam fighters to Jarablus "within 48 hours".
In exchange Jaish al Islam would release hostages it had been holding, it said.
It came a day after a reported chemical attack that killed dozens of people in Douma, which Syria and its ally Russia have strongly denied.
There was no immediate comment from Jaish al Islam. The group blames Syrian regime of carrying out Saturday's chemical attack that left over 40 people dead, including children and women.
SANA reported that buses had been sent to the town to pick up prisoners released by the opposition fighters and to transport rebels to opposition-held territory in north Syria.
Russian operation against 'irreconcilable militants'
Earlier, Russia's military said an operation would begin on Sunday to bring fighters of the Jaish al Islam opposition group out of their besieged enclave of Douma, Interfax reported, after the Syrian regime said the group had asked for negotiations.
The group so far has rejected a Russian offer of safe passage out of Douma, which is near Damascus, to opposition-held areas at the border with Turkey.
Major General Yuri Yevtushenko, head of the Russian peace and reconciliation centre in Syria, said the operation to take "irreconcilable militants" out of Douma would begin on Sunday.
Regime winning back nearly all of Ghouta
Syrian regime leader Bashar al Assad has won back control of nearly all of eastern Ghouta in a Russian-backed military campaign that began in February, leaving just Douma in opposition hands.
After a lull of a few days, regime forces began bombarding Douma again on Friday.
On Sunday, the regime military released a video it said showed troops advancing on Douma from the frontline town of Rihan.
The video purportedly showed regime troops reinforcing positions in Rihan, and moving on the road connecting Ibn Sina Hospital, a hospital in the Adra area, near Douma.
All of Syria's Eastern Ghouta hasn't fallen yet: still 78,000 to 150,000 civilians left in the city of Douma, subject to Assad's siege and airstrikes, while awaiting results of rebel-government negotiations. https://t.co/rGkHBMz3y3 pic.twitter.com/oH9eFTWK8M— Kenneth Roth (@KenRoth) April 7, 2018
Deadly offensive in Ghouta
The offensive in eastern Ghouta has been one of the deadliest of the seven-year-long war, killing more than 1,600 civilians, according to the Syrian Observatory for Human Rights.
Backed by Russia, Assad's forces have scored a series of victories over rebel forces in recent years, often through campaigns of siege, aerial bombardment and ground offensives that have drawn widespread international condemnation.
Syria's seven-year bloodletting has left around 450,000 killed. More than 11 million people — about half the country's prewar population — have been displaced from their homes, including over 5 million who are living as refugees outside Syria, according to the United Nations.
The UN has estimated the material cost of the war damage at close to $250 billion.