Syrian opposition fighters and their families began leaving Eastern Ghouta on Thursday (March 22nd) under the first evacuation deal in the shrinking opposition enclave outside Damascus, AFP reported.

The agreement, announced on Wednesday and brokered by regime ally Russia, could empty one of three opposition-held pockets in the region and mark a major advance in government efforts to secure the nearby capital.

State television said around 1,130 people -- including more than 230 fighters -- had boarded buses from the Eastern Ghouta town of Harasta, until now held by the Ahrar al-Sham group.

A military source said around 2,000 people are expected to leave in total, including around 700 fighters on Thursday.

Ahrar al-Sham spokesman Munzer Fares said the evacuations could last several days.

They followed renewed airstrikes in Ghouta early on Thursday which killed 20 civilians, according to the Syrian Observatory for Human Rights.

Central Damascus lies within mortar range of Eastern Ghouta, and the evacuation deal came after the deadliest opposition rocket attack on the capital in months killed 44 civilians on Tuesday.

Opposition fire on Thursday killed four people in Damascus, state television said.

The fighters and their families will be transported to the north-western province of Idlib, which is held by a myriad of extremist, Islamist and secular groups.

Syrian Reconciliation Minister Ali Haidar told AFP that Ahrar al-Sham had negotiated with the Russian Centre for Reconciliation and that Damascus was not directly involved.

Nawar Oliver, an analyst at the Turkey-based Omran Centre, said fighters in Harasta "were not able to impose a single one of their conditions".

Opposition figures in Ghouta said talks were under way for a deal to evacuate fighters from the enclave's main town, Douma.

Douma is controlled by the Jaish al-Islam group, while a pocket of territory around the town of Zamalka, closer to the capital, is held by Faylaq al-Rahman with a small extremist group presence.

Airstrikes on Zamalka killed 16 civilians on Thursday, the Observatory said.