BEIRUT/AMMAN (Reuters) - Syria’s army is poised to slice rebel-held eastern Ghouta in two as forces advancing from the east link up with troops at its western edge, a pro-Damascus commander said on Thursday.

The government, backed in the war by Russia and Iran, is seeking to crush the last major rebel enclave near the capital in a ferocious campaign that the aid agency Medicins Sans Frontieres (MSF) says has killed more than 1,000 people.

Rebels, who accuse the government of “scorched earth” tactics, said they were deploying more guerrilla-style ambushes in lost territory, trying to stop further advances.

“We came because of the intensity of the bombing,” said Abu Mohammed, a 32-year-old farmer who had left his cows, sheep and farm equipment to join thousands of others fleeing to Douma, further into the rebel enclave.

“It was a miracle that we made it here,” he said, speaking of the heavy air strikes. As for his former home town of Beit Sawa: “It was totally destroyed. Burnt,” he said.

Defeat in eastern Ghouta would mark the worst setback for rebels since the opposition was driven from eastern Aleppo in late 2016 after a similar campaign of siege, bombing and ground assaults.

MSF said on Thursday the offensive had killed 1,005 people and injured at least 4,829. The Syrian Observatory for Human Rights, a war monitoring group in Britain, says 915 civilians have died in the last 18 days, including 91 on Wednesday.

A U.N. official said fighting had reportedly driven the everyone in the towns of Mesraba, Hammouriyeh and Mudeira to seek refuge elsewhere in the rapidly shrinking pocket. They had an estimated population of about 50,000 in December, the official said.

The pro-Damascus commander, who spoke on condition of anonymity because he was not authorized to talk to the media, confirmed a report by the Observatory late on Wednesday that the enclave had effectively been sliced in two.

But Wael Alwan, the Istanbul-based spokesman for Failaq al-Rahman, one of the main rebel groups in eastern Ghouta, denied that the territory had been cut in half. “No,” he said in a text message when asked if the report was correct.

Another rebel spokesman, Hamza Birqadar of the Jaish al-Islam group, said in a tweet on Thursday that insurgents had regained some positions in a counter-attack.

The Observatory reported heavy fighting on several fronts. A military media unit run by the government’s ally Hezbollah also reported that the army had taken the village of Hosh al-Ashari and a military base near Aftaris, both in the southern part of the enclave.

CONVOY

In northern Syria, rebels began to bombard two government-held villages besieged by insurgent forces, killing two children, the Observatory reported.

Plans to send an aid convoy to Ghouta on Thursday were postponed, the International Committee of the Red Cross (ICRC) and the United Nations said.

“Convoys need to come in with food and supplies - and the last convoy was only half unloaded,” Henrietta Fore, executive director of the U.N. children’s agency UNICEF, told Reuters.

The United Nations says 400,000 people are trapped in the towns and villages of eastern Ghouta. They have been under government siege for years and were already short of food and medicine before the assault.

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“We are dying of hunger and our children are dying of hunger. Have pity on us,” said a woman reached in Douma by a voice messaging service, who identified herself as Um Mahmoud.

Russia, President Bashar al-Assad’s most powerful ally, has offered rebels safe passage out with their families and personal weapons. The proposal echoes previous agreements under which insurgents, in the face of military defeat, were permitted to withdraw to opposition-held areas along the Turkish border.

Syrian state news agency SANA reported that a second safe route out of eastern Ghouta, along with one near Douma, had been opened in the southern part of the enclave.

Russia’s defense ministry said on Wednesday some rebels wanted to accept the proposal to evacuate. So far rebels have dismissed it in public and vowed to fight on.

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BATTLES RAGING

Syria’s ambassador to the United Nations in Geneva, Hussam Aala, told the U.N. Human Rights Council on Thursday the assault targeted “terrorist organisations in accordance with international humanitarian law”.

Moscow and Damascus say the Ghouta campaign is necessary to halt deadly rebel shelling of the capital.

Rescue workers and opposition activists in eastern Ghouta have accused the government of using chlorine gas during the campaign.

The government firmly denies this. Damascus and Moscow have accused rebels of planning to orchestrate poison gas attacks in order to draw blame onto the Syrian government.

A Syria-focused medical aid group said there were reports from doctors of a chlorine attack on Wednesday evening. Local rescue workers said gas had affected 50 people.

Social media activists shared videos and photos, which Reuters could not verify, of people with signs of breathing difficulties.

The opposition-run rescue service said two of its rescuers were killed when their ambulance was hit last night, adding its teams were hampered from reaching many victims under rubble.

The narrow point linking rebel territory in north and south parts of eastern Ghouta is all within the range of government fire and impossible for insurgents to cross, meaning the enclave has in military terms been bisected, the commander said.

A rebel fighter with Jaish al-Islam, one of the main factions in eastern Ghouta, said intense fighting was under way.

“Nothing is secure and battles are raging and it’s difficult to predict what will happen,” the fighter, who gave his name as Abu Ahmad al-Doumani, said in a text message to Reuters.