More than 500 dead in fierce Aleppo clashes

The figure included both rebels and government forces that died while attempting to seize control of the northern Syrian city.

Although no exact toll could be given by the Syrian Observatory for Human Rights, the monitoring group said the majority of those killed since July 31 were rebels and jihadists "because of the aerial superiority of the regime and intense Russian airstrikes".

At least 130 civilians had also been killed since the fighting sparked on Sunday, the Observatory chief Rami Abdel Rahman said, noting that the majority of these died in rebel shelling of government-controlled districts.

In Hamdaniyeh, at least seven civilians were killed on Saturday when rebels shelled the government-held neighbourhood.

Leading Syrian rebel groups and announced that the siege of Aleppo was broken on Saturday after fighters captured new districts in the city.

Around 300,000 civilians were trapped in eastern parts of Aleppo, which had been encircled by regime troops and militias, before opposition fighters from Ahrar al-Sham, Jaish al-Islam, the Free Syrian Army and other Islamist and opposition factions launched an offensive.

The anti-regime forces captured the armaments school and most of the artillery school at a large military academy.

The news was announced by the former al-Nusra Front - renamed Jabhat Fateh al-Sham after breaking from al-Qaeda last week - who also declared it had seized a third military position.

"Rebels break Aleppo's siege," wrote the Istanbul-based National Coalition on Twitter. 

The Islamist faction Ahrar al-Sham also confirmed on Twitter that a rebel advance had "opened the route to Aleppo".

The rebels now control a road – passing through a southwestern suburb of Aleppo – which is the last open route into the city. 

This means that rebels have cut off regime forces and open up a new road for their own besieged forces in the city's east. 

Abdel Rahman said the advance left the regime forces "in a very difficult position despite Russian air support".

"This is an existential battle. Whoever wins it will win Aleppo," he said

However, state-run media denied that the rebels captured these areas.

More than 280,000 people have been killed since Syria's conflict erupted in 2011 and millions have been forced to flee, including around five million who have sought refuge in neighbouring countries.