Assad is accelerating his campaign to retake the remaining enclaves his forces have encircled around Syria, which would leave rebels with only their two major strongholds in the northwest and southwest.
Global inspectors from the Organisation for the Prohibition of Chemical Weapons (OPCW) who arrived in Damascus almost a week ago were still waiting early on Friday to visit the site of the suspected poison gas attack.
The Syrian government has control of most of the country, with opposition groups restricted to pockets in the north.
Assad's army retook eastern Ghouta this month, the biggest rebel enclave near Damascus, but a suspected poison gas attack by his regime caused worldwide outrage.
Meanwhile, official SANA news agency reports on Thursday that evacuation of "Jaish al-Islam" terrorists and their families from al-Dmair town in the countryside of Damascus has begun after handing over their heavy and medium weapons as part of the agreement reached with the government. Rebels in the adjoining Beit Sahm area had agreed to withdraw on buses, he said.
Natural disaster in Canada shakes parts of MI
Few people in heavily populated areas nearby reported feeling the temblor, perhaps owing to its depth of 11 miles. Many went to Twitter to share their thoughts - from surprise to humorous - about the Detroit natural disaster .
The area is much smaller than the eastern Ghouta region that Syrian government forces recently recovered in a Russian-backed offensive. Russian Federation and Assad's government deny this.
The army has put military pressure on rebels in Eastern Qalamoun to start negotiations to withdraw, the Syrian Observatory for Human Rights war monitoring group said.
Referring to the latest evacuations, the United Nations said in a note it expected further displacements soon to northern Syria.
The built-up residential area on the southern edge of Damascus was once home to some 200,000 Palestinians, mainly refugees from the 1948 war with Israel and their descendants - as well as tens of thousands of middle-class Syrians.
A commander in the regional military alliance that backs the Syrian government said the Syrian army had begun shelling the jihadist enclave on Tuesday in preparation for an assault. The route was suspended when Islamic State militants had partial control over Iraqi territory but have again become a key arms channel since the militants were routed past year.