Russia, for its part, said its “accurate” strikes had killed 85,000 “terrorists”.
A steadfast ally of Syria’s ruling regime, Russia began carrying out bombing raids in the country on September 30, 2015 – more than four years into the devastating conflict.
Since then, they have killed 18,096 people, according to the Syrian Observatory for Human Rights.
“That number includes 7,988 civilians, or nearly half of the total,” said Observatory chief Rami Abdel Rahman.
Another 5,233 Islamic State fighters were also killed in Russian strikes, with the rest of the dead including other rebels, Islamists and jihadists, the Britain-based monitor said.
Russia’s defence commission published drastically different figures on Sunday.
“All of the air strikes have targeted and are still accurately targeting terrorist targets,” said commission chief Viktor Bondarev, cited by the Russian Interfax agency.
Human rights groups and Western governments have criticised Russia’s air war in Syria, saying it bombs indiscriminately and targets civilian infrastructure including hospitals.
The White Helmets, a Syrian rescue force that works in opposition areas, said in a report released Sunday that it had responded to dozens of strikes by Russia on buildings used by civilians since 2015.
They included Russian bombing raids on 19 schools, 12 public markets and 20 medical facilities over the past three years, as well as 21 of its own rescue centres.
“Russia has flaunted its disregard for agreements over safe zones, no-conflict zones, cessations of hostilities, and de-escalation zones by continuing with airstrikes on civilian spaces,” the White Helmets charged.
Russia has operated a naval base in Syria’s coastal Tartus province for decades, but expanded its operations to the nearby Hmeimim airbase in 2015.
It also has special forces and military police units on the ground in government-controlled parts of the country.
The air strikes were crucial in helping troops loyal to President Bashar al-Assad retake swathes of the country, including second city Aleppo in 2016 and areas around Damascus, the rural centre, and the south this year alone.
“The regime controlled just 26 percent of Syrian territory” when Russia intervened, said Abdel Rahman, compared with close to two-thirds now.
In addition to the Russian and Syrian air forces, warplanes from the US-led coalition fighting IS have also been carrying out bombing raids on Syria since September 2014.
Last week, the Observatory said that US-led coalition air strikes on Syria had killed more than 3,300 civilians since the alliance began operations against IS targets.
The Observatory, which relies on sources inside Syria for its reports, says it determines whose planes carried out strikes according to type, location, flight patterns and munitions involved.
