At the same time, Russian officials say only five citizens may have been killed, and claim they had no relation to Russia’s armed forces.
About 300 men working for a Kremlin-linked Russian private military company Wagner were either killed or injured in Syria last week, according to three sources familiar with the matter.
A Russian military doctor said around 100 had been killed, and a source who knows several of the fighters said the death toll was in excess of 80 men, according to Reuters.
The timing of the casualties coincided with a battle on Feb. 7 near the Syrian city of Deir al-Zor where, according to U.S. officials and associates of the fighters involved, U.S.-led coalition forces attacked forces aligned with Moscow’s ally, Syrian President Bashar al-Assad.
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The casualties are the highest that Russia has suffered in a single battle since fierce clashes in Ukraine in 2014 claimed more than 100 fighters’ lives. Moscow denies sending soldiers and volunteers to Ukraine and has never confirmed that figure.