Air raids by Syrian government warplanes killed 20 civilians, including seven children.
They are due to leave under a United Nations-brokered deal that marks another success for the Assad government, increasing its chances of reasserting control over a strategic area just 4 km (2.5 miles) south of the centre of the capital.
Although the Syrian army claimed it carried out the airstrike that killed Allouch, many in the opposition are convinced Russian Federation was really to blame.
UN Syria mediator Staffan de Mistura, announcing the planned date of the peace talks in Geneva next month, said in a statement yesterday that he aimed to convene representatives of the Syrian government and "the broadest possible spectrum of the Syrian opposition and others".
Syrian authorities forces booby trapped a cluster of farm buildings within the southern Daraa province & detonated the explosives as several Islamic rebel factions gathered at the venue, killing 17 militants, opposition activists stated Sun.The explosion, which happened late Saturday, was the newest blow to the rebels shortly after the assassination the day gone by of a strong rebel leader on the outskirts of Damascus.
Khaled Abdul-Majid, a Damascus-based Palestinian official, said in a statement Sunday that the agreement had stumbled following Allouch's killing.
Zahran was considered as a credible and charismatic leader credited for uniting various Syrian rebel groups. Two other senior rebels, one from Ahrar al-Sham and the other from Faylaq al-Rahman, were also killed in the operation against the headquarters of the Army of Syria.
Jaish al-Islam rose to prominence in Eastern Ghouta and has remained firmly opposed to both Assad and to the Islamic State jihadist group.
Alloush, who was in his mid-40s, was widely known to be supported by Saudi Arabia and Turkey.
Jaysh al Islam, with thousands of trained fighters, is the biggest and seen as the most organized rebel group.
He is blamed by other opposition groups for the December 2013 kidnapping of four prominent activists including human rights activist and lawyer Razan Zaytouni.
Meanwhile, a U.S.-backed coalition of rebels in Syria - including Syrian Kurdish, Arab and Christian groups - captured a major dam on the Euphrates River from the Islamic State group as part of the coalition's march on IS-held areas in northern Syria.
It added that the Islam Army was part of the deal, as its militants were supposed to allow the rebel convoys leaving the southern districts of Qadam and Hajar al-Aswad to pass areas under its control before reaching al-Raqqa or Aleppo.
Parts of the camp, which gained worldwide notoriety past year after a photograph depicted thousands waiting for food in the shelled city, have subsequently been taken by al-Qaeda-linked al-Nusra, as well as pro- and anti-government Palestinian groups.
The large metal cages with men and women inside were then put on pick-up trucks that drove around Damascus suburbs.
Syria has been mired in civil war since 2011, with opposition factions and Islamist terrorist groups such as Daesh and the al-Nusra Front fighting the Syrian Army. The group has launched indiscriminate mortar attacks at areas in Damascus, generally in response to the Syrian government's indiscriminate bombing campaigns against the Eastern Ghouta region.
