Deadly airstrikes halted a Turkish military convoy carrying ammunition after it crossed into northwestern Syria on Monday, bound for the opposition stronghold.
The strikes hit near the highway where the convoy was moving.
It was not immediately clear whether it was Syrian government or Russian warplanes that struck near the convoy but the development marked a sharp escalation in tensions in the northwestern province of Idlib where Syrian troops have been on the offensive for weeks.
Syria's Foreign Ministry slammed Turkey, saying the convoy consisted of armored vehicles loaded with ammunition and was heading to Khan Sheikhoun, a major opposition-held town in Idlib.
Turkey's Defense Ministry said that three civilians were killed and 12 others wounded in the air strike on the convoy, which it said was en route to one of its observation posts.
The ministry said in a statement that the attack violated Ankara's agreements and cooperation with Russia, which it claimed had been told in advance about the convoy.
Turkey's private DHA news agency said Syrian regime planes targeted the route of a Turkish military convoy carrying reinforcement vehicles and personnel. It said the convoy was heading toward two Turkish observation posts in the region when it came under Syrian aircraft fire.
The report said the convoy could not proceed because the route between Maaret al Numan and Khan Sheikhoun was targeted, and sheltered at a safe location.
Turkey has 12 observation posts in and on the edge of the Idlib.
The Britain-based Syrian Observatory for Human Rights said airstrikes believed to be Russian struck near the highway and forced the nearly 25-vehicle Turkish convoy to stop.
It said one fighter from a Turkey-backed faction accompanying the convoy was killed and others were injured.
The Syrian Foreign Ministry called the convoy's incursion a "flagrant Turkish intervention," saying it had reached Saraqeb, a town north of Khan Sheikoun early on Monday.
The ministry said "this hostile behavior of the Turkish regime" wouldn't affect Syrian troops' push into Khan Sheikhoun.