REUTERS, 23rd MAY, 2019 - Thousands more people have fled violence in northwest Syria, the United Nations and a medical agency said on Thursday, as an army assault on the last big rebel enclave met a counter-attack.   

President Bashar al-Assad launched his offensive at the end of April in Idlib and parts of adjacent provinces with an intense bombardment, saying insurgents had broken a truce.   

This week, rebels rolled back some government advances on the main battlefront, retaking the town of Kafr Nabouda.   

Government forces are buttressed by Russian air power, while the main jihadist group that dominates Idlib has been reinforced by Turkey-backed rebels.   

Eight years into the civil war, Assad has retaken most of Syria and rebels still fighting him are squeezed into the northwest. Turkey-backed groups hold a strip of territory on the border, and Kurdish-led fighters hold the northeast.   

This week’s fighting brought a big increase in air strikes, with bombs falling on towns and villages across the southern part of the enclave, said a British-based war monitoring group, the Syrian Observatory for Human Rights.   

Some 600 air strikes hit the rebel enclave on Thursday, the Observatory said, killing six civilians.