Russia on Friday said that Turkish troops who came under fire by the Syrian army were among "terrorists", after at least 33 were killed in Idlib province.
On Thursday "Turkish soldiers who were in the battle formations of terrorist groups came under the fire of Syrian troops," the defence ministry said in a statement.
It said Turkish forces had not communicated their presence in the area, "where they should not have been".
"The Russian air force is not used in this zone," the ministry added.