ISTANBUL - About 1,000 Syrians, including a defecting brigadier-general, have fled to Turkey in the past 24 hours to escape intensifying violence in their country, a Turkish official said on Friday.

The latest group brought the number of Syrian refugees in Turkey to 45,500, up from 44,000 at the end of July, said the official, who asked not to be named. At least 25 military generals are among those who have taken refuge in Turkey.

A 17-month-old uprising in Syria has created a refugee crisis in Turkey and other neighbouring countries. Opposition sources say at least 18,000 people have been killed since the revolt against President Bashar al-Assad began in March 2011.

Turkish officials are concerned about a possible flood of refugees from Syria's biggest city of Aleppo as Assad's forces use warplanes and artillery to pound rebel fighters there.