The return of Aleppo to full government control Thursday is a "great loss" to the five-year revolt against Syria's President Bashar al-Assad, a rebel official said.

"On the political level, this is a great loss," Yasser al-Youssef of the Nureddin al-Zinki rebel group told AFP. "For the revolution, it is a period of retreat and a difficult turning point," he told AFP.