The Syrian army intensified shelling and air strikes on the last rebel enclave in the Syrian capital on Monday, its heaviest bombardment in a two-month military campaign, rebels and witnesses said.
From the strategic Qasyoun Heights that overlooks Damascus, elite units of the army struck Jobar district, some 2 km (1.2 miles) east of the Old City wall and Ain Terma just to the south.
The offensive has dented a Russian-sponsored cease-fire announced two weeks ago in the Eastern Ghouta area to the east of Damascus.
Scores have been injured and at least ten civilians killed in three days of bombardment, civil defence sources said. Less intense shelling hit Zamalka, Harasta and Kafr Btna, also in Eastern Ghouta.
If successful, the campaign would help the army in its eventual goal of regaining Eastern Ghouta, which has been under opposition control for much of the six-year conflict. Jobar is in northeast Damascus and borders the Eastern Ghouta district of Ain Terma.
The army is also using more elephant rockets — inaccurate improvised munitions often made from gas canisters and fired on a high trajectory — insurgents said.
"The elephant rockets are not having mercy on us. We have dug tunnels and fortified our positions so they are unable to advance," said Abu Obada al Shami, a commander from Failaq al-Rahman, the rebel group whose fighters are drawn from the area.
The rebel battle to keep their last foothold in Damascus follows the loss earlier this year of Qaboun and Barzeh districts, located north of Jobar, after intense bombardment.
Before the war began in 2011, more than half a million people lived in Eastern Ghouta, a sprawling mix of towns and farmland.
Two residents said Ain Terma was now a ghost town, with only a few hundred families taking shelter in basements after most former residents fled to other towns in Eastern Ghouta.
"Life is non-existent. Permanent terror and people are not coming out of their basements," said Abdullah al-Khatib, a former electrician, who lives there with his eight-member family.
Rebels accuse the Syrian army and its Iran-backed allies of breaking the Russia-brokered truce in Eastern Ghouta to throw its full weight against Jobar and Ain Terma.
The government has said it will abide by the truces Russia has brokered but says it continues to target Islamist militant factions not covered by the agreement.
"This truce is a lie. The regime has not implemented it.
They are shelling us without interruption using all types of weapons," Abu Hamza, another rebel fighter said.