The head and several leaders of one of Syria’s most powerful rebel groups, Jaysh Al-Islam, have been killed in an air strike in east of Damascus.
The Syrian Army said that the founder of the group, 44-year-old Zahroun Alloush, was among those killed when rockets hit a meeting place.
The Saudi-backed Islamist group is one of the biggest factions and is dominant in the eastern Ghouta countryside.
It recently joined an opposition summit in Riyadh which produced a framework for peace talks with the government.
In a statement carried by state television, Syria’s Army Command said it had conducted the “special operation” that killed Alloush. Some activists have however, suggested it was a Russian air strike.
Jaysh Al-Islam later named Issam Al-Buwaydani, who is also known as Abu Humam as its new leader. He is from Douma, a town to the east of Damascus.
Russia, a key ally of Syrian President, Bashar Al-Assad, has been waging an air campaign in Syria since the end of September.
Moscow insisted it has been targeting Islamic State, but rebels and Western officials said the Russian strikes have mainly been hitting other groups.
Jaysh Al-Islam, whose fighters number tens of thousands, took part in the conference in the Saudi capital which agreed a common approach among disparate rebel groups for UN-backed peace talks planned for January.