Zahran Allouch, the prominent leader of the Army of Islam has been killed in an airstrike.
The Army of Islam is one of the most powerful groups opposing Syrian President, Bashir Al Assad.
The Russian airstrike occurred near Damascus and killed several other rebel leaders.
The Army of Islam is purportedly backed by Saudi Arabia and were responsible for attacks in Damascus in recent months.
As many as 13 airstrikes have hit Damascus in the past week with claims that the airstrikes are killing moremore civilians than rebels.
Peace talks are due next month in Geneva between the Syrian government and the opposition.