The commander of the Syrian regime military campaign, Brigadier General Ghassan Saeed, is reported to have been killed on Sunday near the city of Deir Ez-Zor.
Al Arabiya reported that Saeed, who is an officer at Quiris Military Airport, died when regime forces confronted Daesh in the Syrian desert then advanced on the city of Deir Ez-Zor.
Syrian regime forces are seeking to lift the siege imposed on the city after retaking several sites previously held by Daesh west of Deir Ez-Zor after battles between the two parties.
Meanwhile, pro-regime media sources reported that five other officers were killed in the fighting.
In January the UN's World Food Programme temporarily suspended air drops of vital supplies to Deir Ez-Zor due to heavy fighting. Daesh launched their fiercest attack in a year on the eastern Syrian city in an attempt to isolate it from a nearby military air base.