More than 400 civilians were among the 1,331 people killed in Russian airstrikes in Syria since September, a monitoring group said Friday.
The Syrian Observatory for Human Rights said the civilian toll included 97 children.
The overall toll is double that reported by the watchdog group three weeks ago.
It said 381 DAESH militants were killed, along with 547 insurgents from Syria's al-Qaeda branch, al-Nusra Front, and other rebel groups.
Russia, an ally of Syrian President Bashar al-Assad, says its airstrikes which began on September 30, are aimed at DAESH and other 'extremist' groups.
The Syrian opposition and its backers say Moscow's actions have hit moderate rebels fighting both al-Assad and DAESH.
Military jets, believed to be Russian, on Friday mounted at least 50 raids in the eastern province of Deir al-Zour, killing at least eight civilians, including three children, the Observatory said.
Russia has stepped up its air strikes in Syria after DAESH claimed responsibility for the October 31 downing of a Russian passenger airliner in Egypt.
Saudi Arabia said it will host a meeting next month for Syrian opposition groups to unify their ranks in the run-up to planned peace talks with al-Assad's regime.
Ahmed Ramadan, a member of the Western-backed opposition Syrian National Coalition, welcomed the move and told DPA that a Saudi delegation was expected soon in Istanbul, where the coalition is based, to brief its leaders on the conference to be held in mid-December in Riyadh.
"The Saudi effort is aimed at confronting the Iranian and Russian interference in the Syrian crisis," Ramadan said.
Russia and Iran have rejected repeated calls by the West and Saudi Arabia for al-Assad to step down to end Syria's conflict.