Civilians are fleeing the city of Aleppo in increasing numbers amid a lull in fighting between rebels and Syrian government forces.
The UN refugee agency says almost 150,000 refugees are now registered in four neighbouring countries.
The UNHCR said 6000 have crossed into Turkey in the past week, many of them from the Aleppo area.
The agency said there are now 50,227 refugees registered in Turkey; 45,869 in Jordan; 36,841 in Lebanon and 13,730 in Iraq.
