"All checkpoints along the Syrian border are closing starting today," Hayati Yazici, minister for Customs and Trade, was quoted as saying by the Turkish television station NTV.
A decision to stop traffic between Turkey and Syria came after several border crossings were seized by Syrian rebels seeking to create a buffer zone, Euronews.com said.
Wednesday's move will close the three remaining border gates: Cilvegozu, Oncupinar and Karkamis, the Turkish daily the National Turk quoted an unnamed Turkish official as saying.
It said crossing the borders has become increasingly hazardous for Turkish truckers. The move will halt the passage of vehicles between Turkey and Syria, the National Turk said, adding refugees fleeing Syria cross the border via smuggling routes.
Turkey has 13 border crossing checkpoints along its 900 kilometer (559.2 mile) border with Syria.
Syrian opposition activists said thousands of Syrian troops withdrew tanks and armored vehicles from the Jabal al-Zawiya highlands in the Idlib province near the Turkish border and headed toward Aleppo, the British newspaper The Daily Telegraph said.
Activist Abdelrahman Bakran told the newspaper rebel forces attacked Syrian military forces from the rear as they withdrew from villages near the Aleppo-Latakia road.
Syrian army helicopters strafed neighborhoods in Aleppo and there were reports of intense gun battles between regime soldiers and rebel forces, channelnewsasia.com said.
Aleppo the scene of fierce clashes between rebels and government forces in recent days is the country's industrial and financial center.
Hundreds of families fled the Damascus suburb of al-Tel in the face of fierce artillery and rocket barrages, the British daily The Guardian said.