Assad's heaviest assault on Aleppo

The five tanks covered the corners of Salaheddin Square, firing at rebel fighters trying to make their way through the side streets, desperate to retake the ground they had lost, their task made even more difficult by the helicopter gunships attacking overhead.

This was not the first time that regime forces had sought to break the impasse on the Aleppo frontline by sending in armour. But this time they stayed longer than before, seeking to open a bridgehead for troops to come in and force their way into the parts of the city held by the revolutionaries.

As dusk fell, with the sky lit by amber glows from fires and the sound of gunfire echoing through the buildings, it was unclear whether President Bashar al-Assad's forces would be able to gain a significant advantage in the battle for Syria's biggest city.

Opposition fighters - in cars, trucks, motorbikes and scooters - were pouring in from three directions to force out the enemy, fully aware of what was at stake.

The rebels used rocket-propelled grenades, which have proved to be effective against armour, and Kalashnikovs as they dashed from doorway to doorway. They appeared to have halted the tanks for the time being at least, but the general feeling was that a push may take place by the regime forces once they got more soldiers in place.

"We have the tanks in a trap - these were deliberate tactics," shouted Abu Mohammed Jaffar, a rebel commander, directing his men down an alleyway. His next words, in a tired voice, were nearer to reality: "We can't afford to let them break out: they will then cut off our guys on the front streets of Salaheddin.

"There will be nothing to stop them from getting in to the centre which has wide streets. It will be difficult to fight tanks at such a place."

The regime started their heaviest assault so far on Salaheddin in the morning, tanks and armoured cars moving in after artillery salvoes. It had not captured the neighbourhood within hours, as Syrian state TV had claimed.

Even with their presence in the square, the forces controlled little of the district. However, the penetration of the rebel defence, which had withstood attacks for 11 days, was the first indication that the troops and armour Damascus has been massing were having a telling effect.

State television also declared that "dozens of terrorists had been killed and many more captured." Rebel losses were high, although they appear to be lower than the claim from Damascus. By early evening between 14 and 19 had died, according to reports.

One of those killed was a doctor, a particular loss for the rebels as the medical staff working at makeshift field hospitals are stretched to the limit. Their job is dangerous, and not just because they are working in a combat zone. The burned bodies of three young doctors were found after they had been arrested by the Mukhabarat, the secret police, for treating "terrorists".

The Independent met the latest doctor to die when he was treating the wounded at a mosque last week. Asked about the obvious risks he was taking, the 24-year-old trainee surgeon - whose identity cannot be disclosed, to protect his family - had said: "I have seen guys a lot younger than me dying, suffering terrible injuries.

"I am not even on the frontline with the ambulance drivers; we are just treating the injured, government soldiers as well as the Shabaab (rebel fighters). But this is a strange regime who think doctors are enemies."

Sniper fire was particularly heavy yesterday and unusually accurate, leading to reports resurfacing, without evidence, of Russian and Iranian sharpshooters being brought in. "It is true, absolutely, we have intercepted their conversations in Russian, they are being paid thousands of dollars," insisted Hussein Mohammed Abdali, a tannery worker turned revolutionary.

Lack of information was a continuing problem for the rebels yesterday. On 10th Street in Salaheddin, fighters of the Abu-Bakr Brigade, from the town of al-Bab, were engaged in their routine and ferocious firefight with the enemy, having disabled a tank by rocket-propelled grenades in an ambush earlier.

They were, however, unaware of the tanks on their flanks in the Square, potentially cutting them off from the rest of the opposition force.

"Communications are not good," Abu Amar Idlibi said, tapping his elderly walkie-talkie. "We heard there was fighting in that direction, but we do not know exactly what is going on. We have been told to hold this line."

As he spoke, two shells in succession hit buildings 30m away, half-demolishing one. "As you can see we are being kept busy here; others will have to deal with the tanks behind us. We'll help them, Insha'Allah, if we see out the night."

- Independent