Syrian government forces are close to taking full control of Eastern Ghouta, the last rebel-held area near the capital, Damascus.
Two out of three rebel groups that had been controlling the enclave have already surrendered, with thousands of fighters and their relatives departing for opposition-held areas in the north of the country.
The third rebel group, Jaish al-Islam, which controls the city of Douma, has so far refused to give in.
However, it is understood that Jaish al-Islam is also close to reaching an evacuation deal following negotiations with the Russian army, an ally of Syrian forces.
Al Jazeera’s Zeina Khodr, reporting from Beirut, Lebanon, said on Saturday that talks between Jaish al-Islam and the Russian military had earlier collapsed due to the group’s refusal to be evacuated to Idlib, a northwestern province still largely under rebel control.
“Jaish al-Islam does not have good relations with the rebel groups which dominate Idlib province,” said Khodr.
“What we understand is that they may be sent to an eastern region … close to Lebanon’s border,” she added.
On February 18, Syrian government forces backed by Russian fighter jets tightened their siege on Eastern Ghouta with a heavy military offensive that killed 1,500 and wounded more than 5,000.
Nearly 400,000 people remained in the enclave – under opposition control since mid-2013 – before the latest offensive began.
On Wednesday, the Ahrar al-Sham rebel group agreed to surrender Harasta town after reaching an evacuation deal due to “the bombing and [government] siege and the lack of medicine and the lack of place to move”.
Two days later, Faylaq ar-Rahman, a group controlling the towns of Zamalka, Irbin and Jobar in Eastern Ghouta, announced a similar deal to evacuate fighters and civilians to Idlib.
As part of the deal, a prisoner exchange between Faylaq ar-Rahman and the Syrian government was expected to take place, while the Russian military police would be deployed in the areas that the group controlled.
Syrian state television broadcast live footage of eight Syrian men who were released after being detained by Faylaq ar-Rahman for more than a year.
Around 5,200 Syrians have been evacuated from Eastern Ghouta so far, according to a report by Anadolu news agency on Saturday.
“We will leave Ghouta but one day we will return,” Hazem al-Shami, an evacuee, said. “They have managed to silence the revolution but it will never die.
“We repeatedly asked the international community for help but they didn’t do anything. It’s a very difficult time for us but we will return.”
Syrian state media reported that the army has been removing barriers, landmines and improvised explosive devices along the road to Irbin to open a new corridor for the evacuation.
In the early hours of Saturday, bulldozers removed giant sand barriers from a main road in Harasta so that fighters and their families could be transported to the north.
“It was a very bad situation. The children were hungry because of the siege and scared because of the bombing,” said a mother evacuating Harasta.
“They didn’t have milk. We pleaded with the aid agencies but no one helped us.”
However, those choosing to be evacuated are not heading to a safe place, according to Khodr.
“Idlib is not a safe place; it has been coming under attack from the skies for years now,” said our correspondent.
“It’s also overcrowded. More than a million internally displaced Syrians are there. Most of these people are going to the unknown; many of them will not find any jobs, so it is a very difficult situation for those people.”
Syrian military and Russian air raids on Idlib have increased in the past week, killing dozens of people.
Idlib is also troubled with fighting between rebel groups.
On Saturday, a car bomb exploded at the headquarters for al-Qaeda’s former affiliate in Idlib city, killing at least seven people and injuring 25 others.
According to UN officials, hundreds of thousands of people have been killed in Syria’s seven-year civil war.