Russian steps in Syria are not acceptable for Turkey, President Recep Tayyip Erdogan told reporters on Sunday, Anadolu Agency reported.
Speaking at Esenboga International Airport in Ankara before leaving for France, Erdogan said: "Unfortunately, Russia is now in a serious mistake and I was under the impression that this step will be a sign which will lead it [Russia] to isolation in the region."
Russia began airstrikes on Wednesday to bolster the regime of President Bashar al-Assad. Moscow insists the strikes are targeting Daesh and affiliated terrorist groups, but Western countries and their Gulf allies believe moderate opponents of Assad and civilians are bearing the brunt of Russian bombing.
Erdogan asked: "What is Russia trying to achieve here? There is Assad who conducts state terrorism and unfortunately both Russia and Iran support this person.
"Countries that are collaborating with the [Assad] regime will give an account before history."
Erdogan asked how many refugees are sheltering in Russia and Iran.
Turkey has welcomed Syrian refugees since the beginning of the civil war in March 2011 and is now hosting around two million people under temporary protection regulations.
"Up to now, we have spent $7.5 billion," said Erdogan, adding it is Turkey's "conscientious duty".
The president reiterated the need of a safe zone to be established in northern Syria but added: "It is obligatory to have no-fly zone. Otherwise, it would be an area that is open to deaths."