Turkey's President Abdullah Gul said Thursday that the country reserved the right to defend itself against any threat from neighbouring Syria, amid discussions about the possible deployment of US Patriot missiles.

"Patriots... are being discussed within NATO. It is only natural for us to take any measure for defence reasons," Gul told reporters, but insisted that it was "out of the question for Turkey to start a war with Syria".

And he also hoped that Syria would not act "illogically."

On Wednesday, Turkey said it is in talks with NATO over the possible deployment of Patriot missiles on its soil as part of contingency planning on the security of Turkey and NATO territories.

Foreign Minister Ahmet Davutoglu told reporters in Brussels that it was only "normal" to discuss any defence measures in the face of potential risk from Syria.

Turkey has already beefed up border security with tanks and anti-aircraft batteries in the face of the deadly 20-month conflict in Syria, which has occasionally spilled over onto Turkish soil.

Turkish border units have systematically retaliated to cross-border shelling since Syrian fire killed five Turks on October 3.

One-time allies Turkey and Syria fell out after Ankara joined Arab and Western countries in demanding that President Bashar al-Assad halt his violent crackdown on the popular uprising that erupted in March last year and has now escalated into civil war.