Turkey said Wednesday it is in talks with NATO over the possible deployment of Patriot missiles on its soil amid the escalating conflict in neighbouring Syria, but the prime minister insisted that no request has yet been made.

Foreign Minister Ahmet Davutoglu told reporters during a visit to Brussels that it was only "normal" to discuss any defence measures in the face of potential risk from Syria, according to the state-run Anatolia news agency.

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 into Turkish soil.

Davutoglu would not say if his government was planning to make an official request to the transatlantic military alliance, emphasising that NATO had a responsibility in any case to protect all member states including Turkey.

But Prime Minister Recep Tayyip Erdogan, who is currently in Indonesia, said: "We have not made such request so far," according to Anatolia.

Davutoglu's spokesman Selcuk Unal had said earlier that discussions with NATO were under way as part of "contingency planning on the security of Turkey and NATO territories."

A NATO official in Brussels also said: "At this point we are not aware of any Turkish request."

US State Department spokeswoman Victoria Nuland said Washington had been in discussions for "many months" with Ankara and the North Atlantic Treaty Organization "to look at what other defensive support Turkey might require."

"My understanding is that as of today, we haven't had a formal request of NATO, but as you know, in the past we have reinforced Turkey with Patriots," she told journalists.

Turkey has systematically retaliated to every cross-border shelling since Syrian fire killed five Turks on October 3, also calling an emergency NATO meeting and demanding UN Security Council action over what it called a "heinous" attack.

A Turkish diplomat said it was too early to directly link the possible deployment of Patriots to the Syria conflict, adding that the request for the missiles was within Turkish plans to reinforce its air defence system.

The US-made Patriot system is capable of intercepting both aircraft and missiles.

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.

Turkey is home to over 110,000 Syria refugees in several camps along its border as well as exiled military and political opposition leaders.

But its pleas for a safe haven inside Syria fell on deaf ears at a UN Security Council meeting in August.

Turkey is hoping to secure more backing for its stance from the United States following the re-election of President Barack Obama, after diplomatic sources expressed disappointment with what they saw as a lack of robust action on the Syria conflict by Washington.

Erdogan said Wednesday he now expected the United States to handle the Syria crisis differently, in remarks carried by Anatolia, without elaborating.

Turkey's Milliyet newspaper reported that the United States was considering installing Patriot missiles along the Turkey-Syria border to create some form of no-fly zone, as long as there was no involvement of ground troops in Syria.