Four Turkish soldiers have been killed and nine wounded in shelling by Syrian government forces in Syria’s north-western Idlib province, Turkey says.
It said up to 35 Syrian soldiers “were neutralised” in retaliatory fire. There is no comment by the Syrian government.
Thousands of people have been fleeing an offensive by Syrian troops and their Russian backers against the last opposition stronghold in Idlib.
Many civilians have moved towards the border with Turkey.
Turkey says its troops in Idlib are to prevent clashes.
Turkey and Russia, a key ally of Syrian President Bashar al-Assad, signed a de-escalation deal for Idlib in 2018, but it has been frequently violated.
On Monday, Turkish President Recep Tayyip Erdogan warned Russia “no to stand in our way”, referring to Ankara’s dealing with Damascus over the shelling.