'They fear the regime will take revenge,' say Syrian opposition activist

A five-year-old boy was among the latest casualties in Aleppo (AFP/Getty Images)

Amar Mohammed Yusuf was reaching for the last remaining clip of ammunition for his Kalashnikov when he was hit on the leg by shrapnel. As his comrades tried to move him to safety, a warplane dived down above them, before banking and veering off. Just as they had breathed sighs of relief, a helicopter gunship opened fire, the blast flinging the fighters head first into a ditch.

The impending "mother of all battles", as the pro-regime newspapers in Damascus has declared, with dire warnings from the US administration that a "massacre" will follow, appeared to be taking place incrementally rather than in one massive assault by Bashar al-Assad's forces. Troops were moving into rebel-held areas, with attack helicopters used to blast through defences. The heaviest fighting was in the Salaheddine district.

The bloody struggle for Syria's largest city, a hugely important strategic and symbolic prize in this vicious civil war, has spread into the surrounding areas. The aircraft Mr Yusuf and fellow rebels came across were in Al-Bab, 15 miles to the east, which had become the focal point of a struggle between the opposing sides to open up supply routes.

The satellite town is being bombarded daily from a military base on the outskirts. The sustained barrage is also preventing about 700 fighters from the rebels' Free Syria Army from joining their comrades inside Aleppo where regime troops were forcing back revolutionaries who appear to be running short of ammunition and have had to retreat.

Two days previously, the rebels had attacked a main security checkpoint at Bustan al-Joz in an attempt to take over the business district. This, they believed, would have been a psychological blow to the regime and may finally convinced its supporters in the trading community that they were backing the wrong side.But the rebels had not been able to hold the position and the regime had begun to shell residential neighbourhoods being held by the revolutionaries.

By the afternoon, soldiers had moved into the Hamdaniyeh area in the centre of the city, where the rebels put up strong resistance. "People are frightened. We have had thousands of them, whole families who have gone. Others can see that the rebels are falling back, and they are worried because they fear the regime will take revenge," said Khalid al-Mussa, an opposition activist.

"It is a strategic move. We cannot fight tanks and helicopters. There is no point in dying needlessly," said Rahim Ali Qubuddin, a former architect.

It is a sign of the importance the regime in placing on the revolutionaries being denied reinforcements that warplanes were deployed over Al-Bab. The opposition, too, is desperate for a breakthrough, trying to charge its way into the military camp. The Independent on Sunday accompanied a group of fighters who destroyed two tanks and three trucks during the assault.

Two soldiers who had fled from the base on Friday claimed that morale inside was extremely low. Omar Mukhdaid and Khalid Yusuf, both 20, conscripts of 11 months' service, had been waiting for a chance to defect which they took on Friday from the Al-Bab base.

A major in the opposition's Free Syria Army, Yusuf Al-Hadeed , said: "We can't leave the people of this place undefended. The regime is trying to keep us tied up here, but as soon as we take care of the military base, we'll be moving in there in the next few days."