More than 18,000 people, nearly half of them civilians, have been killed in Russian airstrikes on Syria since Moscow began its intervention exactly three years ago, AFP reported Sunday (September 30th).

Russia, for its part, said its "accurate" strikes had killed 85,000 "terrorists".

Syrian regime ally Russia began carrying out bombing raids in Syria on September 30th, 2015, which have since 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 of Iraq and Syria" (ISIS) fighters also were killed in Russian strikes, with the rest of the dead including other opposition fighters, including members of extremist factions, the Observatory said.

Russia's defence commission published drastically different figures on Sunday.

"All of the airstrikes 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.

The White Helmets said in a report released Sunday it had responded to dozens of strikes by Russia on buildings used by civilians since 2015.

They included 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.