Syrian rebels and their families have begun leaving a key town in the besieged Eastern Ghouta area as part of an evacuation deal with the government.

Some 1,500 fighters from the Ahrar al-Sham faction and 6,000 civilians are to be transported from Harasta to the northern rebel-held province of Idlib.

The evacuation deal is the first agreed since pro-government forces stepped up an assault on the enclave a month ago.

The exodus came after soldiers and allied militiamen drove rebel forces out of about 70% of the region, cutting it into three pockets - one of them around Harasta.

The implementation of the evacuation deal, which was brokered by the government's ally Russia, began on Thursday morning with a prisoner exchange.