Russia's military has said its air strikes in eastern Syria this week killed more than 300 Islamic State militants.
Moscow has been a major backer of Syria's President Bashar Assad, whose government troops have been advancing in the eastern province of Deir el-Zour against IS under the cover of Russian air strikes.
Meanwhile, Kurdish-led Syrian Democratic Forces are also marching against the Islamic State, backed by the US-led coalition.
Russia's Defence Ministry said in a statement early on Tuesday that its air strikes just outside Deir el-Zour, on the eastern bank of the Euphrates River, killed more than 304 IS fighters and injured another 200.
The ministry said the air strikes also hit and destroyed an IS training centre, as well as artillery positions, tanks and ammunition depots belonging to the militants.