Turkey has scrambled two F16 fighter jets to its border with Syria after a reported incident in a small frontier town.
Azmarin, on the Syrian side, has seen intense fighting between Syrian rebels and regime forces in recent days.
Reports say the town came under renewed attack on Friday from a Syrian government helicopter.
Hours earlier, 250 tanks and troop reinforcements were dispatched to the border.
The violence from the 19-month Syrian uprising has regularly spilled into Turkey.
The most notable incident came nine days ago when Syrian mortar fire landed in a Turkish border town killing five civilians.
Within hours, Ankara authorised its military to strike targets within Syria.
On Wednesday, the head of the Turkish army said his forces would respond “more forcefully” if attacks continued beyond Syria’s borders.