Turkey is considering setting up a \"security\" or \"buffer zone\" along its border with Syria after withdrawing its ambassador to Damascus. Ankara also warned its citizens inside the neighbouring country to return home. The move comes as Syrians continue to flee across the border into Turkey. There are an estimated 14,700 refugees in Turkey, with 1,000 having arrived in one day this week. \"On the subject of Syria, a buffer zone, a security zone, are things being studied. It would be wrong to look at it from only one perspective,\" said Prime Minister Tayyip Erdogan on Friday. Turkey has said that in any operation it would need some form of international agreement and involvement. A buffer zone inside Syria would need to be secured. Without at least tacit Syrian government acceptance, that could bring Turkish forces, the second biggest in NATO, into confrontation with Syrian troops. Fighting has moved closer to the Turkish frontier, with a government assault in Syria\'s northwestern Idlib region.