Sick and injured civilians left a rebel enclave in Syria's eastern Ghouta on Tuesday under the first medical evacuation since one of the deadliest assaults of the seven-year war began nearly a month ago.

In another sign of success in the government's mission to retake all rebel-held territory near the capital, the army also evacuated hundreds of fighters and their families from a separate small rebel-held pocket south of Damascus.

In the north of the country, on another main front, Turkey's military said it had encircled the town of Afrin, a big advance in its offensive against Kurdish fighters. Government forces also pounded a rebel-held area in the south for a second straight day, potentially reopening yet another front.