An agreement has been reached to evacuate fighters from the hardline group formerly known as Jabhat al-Nusra from Yarmouk, in the southern suburbs of Damascus, to rebel-held Idlib province.
The agreement is the second phase of an earlier deal to evacuate people from two towns besieged by rebels, and two towns besieged by pro-government forces, the first phase of which was implemented last month.
"Activists in the area told us that green buses arrived to Yarmouk and left carrying dozens of Nusra Front fighters along with their families," said Al Jazeera's Hashem Ahelbarra, reporting from Gaziantep along the Turkey-Syria border.
"The operation will continue for some days, and then the Syrian army is expected to take over the part of the camp that was under the control of al-Nusra."
Most of the nearly 50 fighters were wounded, according to the Beirut-based Hezbollah-affiliated television channel al-Manar.
Hezbollah, also from Lebanon, is a close military ally of Syrian President Bashar al-Assad.
Jabhat al-Nusra was the official branch of al-Qaeda in Syria until a year ago when it broke formal allegiance and renamed itself. It has since joined a number of hardline groups under the new name Tahrir al-Sham.
Both Jabhat al-Nusra and later Tahrir al-Sham have at times fought alongside other rebels, including those that operate under the banner of the Free Syrian Army, against the government and at times have clashed with them.
Yarmouk, in the southern suburbs of Damascus, is the location of a large Palestinian refugee camp. Parts of the area are held by the government, parts by rebels including Tahrir al-Sham, and parts by Islamic State of Iraq and the Levant (ISIL, also known as ISIS).
An earlier deal involved evacuating civilians from the rebel-besieged Shia-Muslim towns of Kefraya and al-Fouaa in Idlib province, in return for the departure of civilians and rebel fighters from the government-besieged areas Zabadani and Madaya, near Damascus.
Completed late last month, that agreement was the largest and most complex so far in a series of evacuation deals for besieged areas that have grown more common over the past year in Syria's bloody six-year war.
While Assad's government in Damascus has praised such deals as a way to reduce bloodshed, the rebels have condemned them as a means to impose demographic change by forcing large numbers of civilians to leave pro-opposition areas.
The United Nations, which has not been party to the agreements, has also voiced concern that the evacuations amount to forced displacement.