"We urge the Turkish side, in order to avoid incidents, to cease support of the actions of terrorists and handing them arms," the Russian defence ministry said in a statement.

Russia, which backs Syrian President Bashar al-Assad, accused Turkey of aiding rebels fighting government forces in the northwestern Idlib province by firing artillery as the rebels carried out an attack.

Moscow said that on Syria's request its bombers carried out strikes on "terrorist armed formations," allowing the Syrian forces to repel the attack.

Separately, Turkey said two of its soldiers had been killed in an air strike in Idlib, blaming the Syrian regime.

The Russian defence ministry said it told Ankara that it had spotted Turkish artillery firing on Syrian units, wounding four soldiers.

"We note this is not the first case of support for rebel fighters by Turkey," the defence ministry said.

Russia on Wednesday warned Turkey against attacking Syrian forces after President Recep Tayyip Erdogan threatened to launch an operation in Syria's Idlib region.