Zaher Hassoun, whose family and friends are all still inside Harasta, told MEE: "The last I heard from my family and friends in Harasta was Saturday night, just before the government forces and pro-Assad militia surrounded the town".
The continued attacks are an attempt by the government to pressure the insurgent groups into so-called "evacuation deals".
Rebel-held parts of Ghouta are under a crippling government siege that has made it hard for its estimated 400,000 residents to access food and medicine.
Despite a recent UN Security Council resolution calling for a cease-fire in Syria, the regime and its allies on March 3 began a major ground operation - backed by Russian air power - aimed at decisively capturing Eastern Ghouta, an opposition-held suburb of Damascus. But Faylaq al-Rahman, one of the two main rebel groups in the region, issued a statement rejecting the prospect of an exit, the AP said.
The Russian military said late on Sunday that 52 civilians, including 26 children, had been evacuated from the town of Misraba, according to Reuters.
The draft resolution would allow "safe, unimpeded and sustained access" for humanitarian aid convoys and "safe, unconditional, medical evacuations in Eastern Ghouta".
In an apparent sign of local discontent with the rebel policy of holding out, the Syrian Observatory for Human Rights monitoring group reported that hundreds of people protested in the town of Kafr Batna to demand a deal to end the onslaught.
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A Syrian Kurdish official says thousands of people are fleeing the northern town of Afrin as Turkish troops and Turkey-backed opposition fighters get closer to the besieged Syrian town.
The Syrian government has denied using chemical weapons.
As the differences lingered, regime forces have splintered eastern Ghouta towns and villages into three isolated pockets.
"We have made it very clear that it would be very unwise to use gas against people, civilians on any battlefield", Mattis told reporters during his trip to Oman.
The US ambassador recalled that US President Donald Trump had ordered missile strikes on a Syrian air base in April past year in retaliation for a sarin gas attack blamed on President Bashar Assad's forces.
She recalled the USA warning after last year's sarin gas attack on Khan Sheikhoun, which an expert panel blamed on President Bashar Assad's government, that it would take action if the council didn't.
Nikki Haley said that since the Security Council adopted a resolution 15 days ago demanding a cease-fire throughout Syria without delay there have been three allegations of chlorine gas attacks during a stepped up military campaign against rebels.