BEIRUT (Reuters) - Insurgents in the last area outside Syrian government control near Damascus agreed on Friday to withdraw, but the army’s bombardment continued pending a full surrender deal, state media and a war monitor reported.

The development heralds another advance for President Bashar al-Assad’s push to retake remaining enclaves and strengthen his position around the capital after retaking eastern Ghouta this month.

Large puffs of smoke could be seen on state television rising from a row of buildings as an artillery salvo struck home before one collapsed in a cloud of dust, accompanied by the rattle of automatic fire and the sound of distant blasts.

Assad is in his strongest position since early in the seven-year war despite U.S., British and French air strikes on April 14 - their first coordinated action in the war.

The attacks were to punish Assad for a suspected gas attack they say killed scores of people during an advance that captured Douma - the rebels’ last redoubt in eastern Ghouta.

But the single volley of raids, hitting three targets far from any frontline, had no effect on the wider war which has killed 500,000 people and made more than half of Syrians homeless.

International inspectors from the Organisation for the Prohibition of Chemical Weapons (OPCW) who arrived in Damascus nearly a week ago were still waiting early on Friday to visit the site of the suspected poison gas attack.

However, a Reuters witness saw a vehicle with licence plates used by international organisations and escorted by Russian military police near the site in Douma on Friday, three days after U.N. security personnel doing reconnaissance for the OPCW inspectors was forced to turn back because of gunfire.

Syria and its ally Russia deny using chemical weapons in the assault on Douma. The Western countries say the Syrian government, which now controls the town, is keeping the inspectors out and may be tampering with evidence, both accusations Damascus and Moscow deny.

Physicians for Human Rights, a U.S.-based rights group, voiced “grave concern” over reports that Douma hospital staff had faced “extreme intimidation” after the area came back under government control to stop them talking about the incident.

DISPLACEMENT

The surrender of the enclave in south Damascus, which includes the Yarmouk Palestinian refugee camp, Hajar al-Aswad district and neighbouring areas, will bring the entire area around the capital back under Assad’s control.

Under the deal, Islamic State fighters, who control part of the enclave, will leave for territory the group controls in eastern Syria, while other factions leave for opposition territory in the north, state media reported.

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Sporadic shelling persisted, the Syrian Observatory for Human Rights war monitor said. State television said the military campaign was continuing because insurgents had not agreed to all details of the surrender. The Observatory said it was because some of the Islamic State fighters still rejected the deal.

Yarmouk was the biggest camp for Palestinian refugees in Syria before the war. Although most residents have fled, up to 12,000 remain there and in the neighbouring areas under jihadist or rebel control, said the U.N. agency that helps them.

“There are reports that large numbers of people have been displaced from Yarmouk Camp to the neighbouring area of Yalda. There are also reports of civilian casualties,” said Christopher Gunness, the spokesman for the U.N. agency responsible for Palestinian camps.

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Jihadist shelling of an adjoining neighbourhood injured five people, Damascus police were cited as saying early on Friday by state television.

Rebels on Thursday began pulling out of Dumayr, an enclave northeast of Damascus, under a surrender deal with the government. Insurgents in another enclave nearby - Eastern Qalamoun - said they had also agreed to withdraw.

Thousands of civilians, including the fighters’ families, are expected to leave with them for northern Syria before the areas come back under Assad’s rule under deals similar to others carried out across the country as government forces advance.

The United Nations has voiced concern that such “evacuations” involve the displacement of civilians under threat of reprisals or forced conscription. The government denies that.

“The U.N. expects further displacements in the near future to northern Syria from other locations controlled by non-state armed groups where negotiations reportedly are happening,” the world body said in a humanitarian note.

Conditions in the opposition-held pocket of northern Syria where the displaced will go are poor.