It said among those killed was Abu Muhammad al-Shimali, the so-called Emir of Deir Ezzor and the "Minister of War" who oversees foreign fighters at IS.
Islamic State faces uphill 'branding war' in Afghanistan, Pakistan
"As a result of a precision airstrike of the Russian air forces in the vicinity of Deir Ezzor city, a command post, communication centre and some 40 ISIS fighters have been killed," the Russian defence ministry said in a statement on Facebook.
"According to confirmed data, among the killed fighters are four influential field commanders including Deir Ezzor emir Abu Mohammed al-Shimali," the ministry said.
Islamic State chief Baghdadi killed: Syrian Observatory
Gulmurod Khalimov, a native of Tajikistan who is known as the IS group's Minister of War, suffered a 'fatal injury', the ministry added.
Khalimov headed the Tajik interior ministry's special forces unit before joining IS in 2015. Backed by Russia, Syrian troops on Tuesday broke through a years-long siege imposed by IS militants on tens of thousands of civilians in Deir Ezzor.
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