Syrian Air Force intelligence chief Iyad Mando was killed on Monday, opposition websites reported. There was no immediate confirmation of the report.
The intelligence branch of the Syrian air force is considered one of the strongest bodies in the state.
Also Monday, Turkey temporarily closed its embassy in Syria, further isolating President Bashar al-Assad, whose forces again bombarded the battered city of Homs with mortars in an effort to quell unrest.
At least 70 people were reportedly killed across Syria on Sunday in various battles.