Turkey has warned it will retaliate if Syrian aircraft enter its airspace amid a third day of air strikes by Syrian forces against rebels along the border with Turkey.

Turkey said several villages west of Ceylanpinar which is opposite the Syrian town of Ras al-Ayn have been evacuated to protect residents from any spillover of fighting.

Turkey's defence minister, Ismet Yilmaz, indicated that Turkey would use military force in response to any incursions by Syrian aircraft. Last month, Turkish artillery fired on targets in Syria after Syrian shells landed inside Turkey and killed several Turkish civilians in one instance.

"The necessary response will be given to Syrian planes and helicopters that violate our border," Yilmaz said.

Ras al-Ayn is in the north-eastern Syrian province of al-Hasaka, an oil-producing region where the population is mostly Kurdish.

The violence in Syria has killed more than 36,000 people since an uprising against president Bashar Assad's regime began in March 2011. Hundreds of thousands have fled the fighting into neighbouring Turkey, Jordan, Lebanon and Iraq. Another 11,000 escaped into Turkey last week following the surge of fighting at Ras al-Ayn.