Several Turkish troops were wounded on Sunday in Syria's Idlib province after pro-Damascus forces targeted a Turkish military convoy with heavy artillery, prompting it to retreat northwards, the Syrian Observatory monitoring group reported.
Turkey has sent thousands of troops to Idlib in the last few weeks after a stepped up campaign by President Bashar al-Assad to re-take the last rebel stronghold prompted nearly a million Syrians to flee for the Turkish frontier.
So far 16 Turkish soldiers have been killed since reinforcements began entering northern Syria earlier this month, raising the prospect of broader conflict.
The Observatory said a fresh Turkish military convoy of about 65 vehicles entered northern Syria on Sunday and headed to the southern Idlib area of Jabal Zawiya before being pushed back by the shelling and Russian air strikes.
After Russia and Turkey, which support opposite sides in the nine-year war, failed to reach an agreement in the last two weeks over Idlib, Turkish President Tayyip Erdogan has vowed to push back Syrian government forces if they press on.
Turkey already hosts 3.7 million Syrian refugees and says it cannot handle another wave.
The Observatory said about 2,765 Turkish military vehicles and 7,600 Turkish soldiers had moved into northern Syria since Feb. 2.