An estimated 2,000 people, including 620 rebels and their families, began an evacuation from a besieged town southwest of the Syrian capital on Wednesday under a deal with the government, local officials told the AFP news agency.

"The buses of rebels have begun moving," said Hassan Ghandour, a member of the local committee overseeing the deal in Moadamiyat al-Sham, also referred to as al-Moadamyeh.

He said the buses held rebels as well as their family members and would head to Idlib province, northwest of Damascus.

There was no confirmation from rebel forces in the area.

Moadamiyet al-Sham has been under a devastating government siege since early 2013. An intitial agreement was struck during a September ceasefire to begin evacuations, with several busloads of civilians being removed from the town.

Syria's government has pushed such deals, which typically see rebels leave in exchange for an end to their encirclement. Many rebel sympathisers have accused the government of instagating a form of ethnic cleasning.

Another member of the local reconciliation committee told AFP on Wednesday that the latest batch of evacuees - rebels and civilians - numbered about 2,100 people.

Any remaining rebels would hand themselves in to Syrian authorities "to have their status regularised", the member said.

"Then, the Syrian army will enter the town and state institutions will return to it. Infrastructure like water and electricity networks will be repaired beginning on Sunday," the member added.

The town was one of several due to get humanitarian aid in the country-wide September pause in hostilities. Activists reported however that Syrian government soldiers looted UN aid convoys, replaced the contents with spoiled food, and then sent it on.

The @UN finally sends aid to besieged #Moadamieh...looking like this and totally unfit for human consumption !! pic.twitter.com/jQ6pEWm8Nr — هادي العبدالله Hadi (@HadiAlabdallah) September 19, 2016

Meanwhile, French President Francois Hollande said on Wednesday he would do everything possible to try to extend a ceasefire in eastern Aleppo, in northern Syria, when he discusses the issue with Russian President Vladimir Putin and Chancellor Angela Merkel in Berlin this evening.

A plan to pause fighting for eight hours in rebel-held east Aleppo from 5am GMT on Thursday has been announced by government ally Russia - with no word from the Damascus government or rebels that they intend to honour the deal.

"As we speak bombings are still taking place. It's true a truce was announced and it's been 24 hours. I will do everything tonight with Chancellor Merkel so that this truce is extended," Hollande said after meeting representatives from rebel-held areas of Aleppo.

The UN had earlier dashed hopes that a prospective ceasefire in east Aleppo could provide humanitarian relief for besieged civilians, saying all sides needed to back an extended truce before aid convoys could roll.

"Before we can do something really meaningful... we need assurances from all parties," said Jens Laerke, spokesman for the United Nations humanitarian agency (OCHA) in Geneva.

"We need a minimum of 48 hours," he added, stressing that Russia's time-limited deal would not be sufficient for UN teams to mobilise.