The Russian Defence Ministry said on Friday Abu Bakr al-Baghdadi was killed in a Russian strike in late May along with other senior group commanders.
If confirmed, it would mark a major military success for Russia, which has conducted a military campaign in support of Syrian president Bashar Assad since September 2015.
The ministry said the air raid on May 28 that targeted an IS meeting held on the southern outskirts of Raqqa in Syria also killed about 30 mid-level militant leaders and about 300 other fighters.
The ministry said the strike came as IS leaders gathered to discuss the group’s withdrawal from Raqqa, the group’s de facto capital.
It said the military began planning the hit after getting word that the IS leaders were going to gather for a meeting to plan their exit to the south.
The Russian military sent drones to monitor the area and then dispatched a group of Su-34 bombers and Su-35 fighter jets to hit the IS gathering.
“According to the information that is being verified through various channels, IS leader Abu Bakr al-Baghdadi also attended the meeting and was killed in the airstrike,” it said in a statement.
The ministry added that it had warned the US of the coming strike.
The ministry said among other militant leaders killed in the raid were IS leaders Abu al-Khadji al-Mysri, Ibrahim al-Naef al-Khadj and Suleiman al-Shauah.