He saw thousands of people on the move, with no shelter or medical support. The government offensive is the latest of at least four launched with Russian air support in the past two weeks. Aside from the Aleppo countryside, they are taking place in mostly rural areas north of the cities of Homs and Hama, and in the north of the coastal province of Latakia. Rebel fighters - not including jihadist militants from Islamic State (IS) - had penetrated most of these strategically important areas earlier this year. Their gains prompted Russia to launch an air campaign to bolster President Bashar al-Assad in September, and also reportedly led Iran to deploy hundreds of combat troops. Tehran has previously only acknowledged sending military advisers.
Syrian troops have gone on the attack this month, taking advantage of Russian air strikes
'Sky filled with jets'
Dr Zoabi told the BBC's Newsday programme that he had seen at least 70,000 people on the move in the countryside south of Aleppo. "We saw only people who do not have even tents, any shelter, whatever. People were asking for some food, sandwiches even," he said. "There is no medical support." "The shelling is so fierce. The sky was filled with jet fighters, with helicopters, and people are terribly scared. They are scared to death." The Syrian Observatory for Human Rights said government forces, backed by Syrian and Iranian militiamen and fighters from Lebanon's Hezbollah movement, had taken control of three hills near the town of Khan Tuman.
Much of Aleppo, once Syria's commercial and industrial hub, has been devastated by fighting
Rebels from the Western-backed Free Syrian Army meanwhile told the Reuters news agency that they had received new supplies of US-made anti-tank missiles since the assault began, though not enough to repel it. The government's forces appear to be pushing towards the motorway that links Aleppo with Latakia and Hama provinces, rebels say. Aleppo is about 50km (30 miles) from the border with Turkey. The city, once Syria's commercial and industrial hub, has been divided in roughly two since 2012, with the government controlling the western half and rebel factions holding the east. On Sunday, Turkey's Prime Minister Ahmet Davutoglu warned European leaders that the offensive south of Aleppo, as well as attacks in the area by Islamic State militants, could "cause another wave of refugees".
Turkey's prime minister says the Aleppo offensive could "cause another wave of refugees"