The number of registered Syrian refugees in other Middle Eastern countries and in north Africa has topped half a million, according to the UNHCR.
The United Nations refugee agency says around 3,000 new people are seeking help and asylum every day.
One thousand crossed into Jordan at night over the past few days, arriving in bad weather without proper winter clothing.
Lebanon has the highest number – more than 150,000 – followed by Jordan and Turkey, says the agency which is based in Geneva.
It believes the actual number of refugees is far higher. Hundreds of thousands are thought to have crossed into neighbouring countries without coming forward to register for assistance.
Only about 40 percent of registered refugees are living in camps. Most are in rented housing, with host families or in communal centres.