DOUMA/ BEIRUT - Syrian regime forces on Saturday cut off the largest town in Eastern Ghouta from the rest of the opposition enclave in a blow to beleaguered rebels defending their last bastion near Damascus.

More than 1,000 civilians have been killed since Syria’s government launched a brutal offensive on the rebel-controlled Eastern Ghouta enclave nearly three weeks ago, a war monitor said on Saturday.

“The death toll has gone up to 1,002 civilians, after eight people were killed today in Harasta and Arbin,” said the Syrian Observatory for Human Rights.

Rescue workers on Saturday pulled the bodies of 17 people, including members of three separate families - from under the rubble of destroyed buildings in Douma.

Douma is the largest urban centre in Syria’s Eastern Ghouta, and regime forces on Saturday were able to isolate it from the rest of the opposition bastion.

Government troops and allied militia have recaptured half of the besieged region in a blistering assault launched on February 18.

At least 215 children are among those killed since then, the Britain-based Observatory said.

Shelling and air strikes slammed into Douma throughout the day Saturday, trapping residents inside cellars transformed into makeshift bomb shelters, an AFP correspondent in the town said.

Rescue workers and medics were struggling to navigate the town’s rubble-littered roads to reach the wounded and take them to field clinics.

They have pursued a divide-and-conquer strategy, eating away at rebel-held towns and successfully isolating Ghouta’s main town of Douma on Saturday.

Regime fighters seized control of the road linking Douma with the town of Harasta further west, and also captured the town of Misraba, according to the Syrian Observatory for Human Rights.

“Regime forces have therefore divided Eastern Ghouta into three parts - Douma and its surroundings, Harasta in the west, and the rest of the towns further south,” the Britain-based monitor said.

Shelling and air strikes slammed into Douma on Saturday, trapping residents inside cellars transformed into makeshift bomb shelters, an AFP correspondent in the town said. Rescue workers and medics were struggling to navigate the town’s rubble-littered roads to bring wounded residents back to field clinics.

Douma’s opposition-run local council issued an urgent “distress call” on Saturday to international organisations. “The bomb shelters and basements are full, and people are sleeping in the streets and in public gardens,” the statement said.

“For three days, it has been hard to bury the dead because of the intense bombing on the cemetery,” it added. Eastern Ghouta is the last remaining opposition-controlled zone on the outskirts of the capital, and government troops have zeroed in on it in order to secure Damascus. Rebels in recent days tried to slow the advance with an attempted counter-offensive, but President Bashar al-Assad’s forces steamrolled their efforts.

Syrian state television on Saturday reported the army had “intensified its operations... and was advancing in three main zones.” It broadcast live footage from a neighbourhood in Misraba recently recaptured from the army.

Dozens of civilians including women and toddlers could be seen in a dark basement, surrounded by troops.

One elderly man broke down into tears as he told state television that his family had fled to Douma under fierce bombardment. The offensive has killed more than 975 civilians, including more than 200 children, and wounded several thousand people, according to the Observatory, which relies on a network of sources on the ground.

Eastern Ghouta is home to around 400,000 people, in desperate need of humanitarian assistance after the five-year siege made food and medical aid exceedingly rare.

On Friday, a joint aid convoy of the International Committee of the Red Cross, the United Nations and the Syrian Arab Red Crescent delivered food aid to hunger-stricken residents. It was the second convoy in one week, after deliveries on Monday were interrupted by heavy bombardment. The UN refugee agency’s Syria representative, who entered Ghouta with Monday’s convoy, said the area was “on the verge of a major disaster”.

“I’ve never seen such scared faces in my life,” Sajjad Malik said. He described seeing a five-storey building that had been reduced to rubble, with a powerful stench emanating from several bodies trapped underneath.

In addition to clashes around Douma, fighting on Saturday raged to the west near the town of Medeira and further south near Hammuriyeh, Saqba, and Efteris. Two Islamist groups are the most prominent rebel factions in Ghouta, but jihadists from Hayat Tahrir al-Sham (HTS) - once linked to Al-Qaeda’s Syria branch - also have a presence.

On Friday, 13 HTS members and their family members were bussed out of the enclave. Rebels said they would be taken to the HTS-controlled northern province of Idlib, in an arrangement struck following consultations with the UN and international players.

Such evacuation deals have been repeatedly agreed in Syria’s seven-year war, most notably in the second city of Aleppo in late 2016. After a ferocious month-long government assault, thousands of rebel fighters and civilians were bussed out of the city’s east.

That paved the way for Syria’s government to announce the full recapture of Aleppo - the largest defeat to date for the fractured opposition movement.

Syria’s conflict erupted with protests against Assad but has since developed into a full-blown war that has drawn in global powers.

Russia has intervened on Assad’s behalf while Turkey has backed rebels against his regime, rival jihadists and Kurdish forces. On Saturday, Ankara-backed rebels advanced against Kurdish militia in northwest Syria, coming to within two kilometres (just over one mile) of the flashpoint town of Afrin, according to the Observatory. The move came as Turkish President Recep Tayyip Erdogan threatened again to “purge” Kurdish militia from the town.