Residents walk through rubble in worn-torn Aleppo
Residents walk through rubble in worn-torn AleppoReuters

(AFP) - More than 300 civilians have been killed in a three-week surge of fighting and bombardment in Syria's devastated Aleppo city, a monitoring group said on Saturday.

The battle for Syria's second city has killed 333 civilians since July 31, when rebels launched a major push to break a government siege of districts under their control.

The toll includes 165 civilians -- among them 49 children -- killed in opposition fire on the city's government-held western districts.

Another 168 civilians died in Russian and regime air strikes and shelling on its rebel-controlled eastern neighborhoods, the Observatory said.

Russia has been carrying out air raids in support of President Bashar al-Assad's forces in Syria since September 2015.

Another 109 people were killed in bombardment across the rest of Aleppo province during the same period, the Britain-based monitoring group said.

Once Syria's economic hub, Aleppo city has been ripped apart by violence since mid-2012, with warplanes bombarding the east and rockets raining down on the west.

Air strikes pounded Aleppo's southern edges on Saturday, and the intense battles there could be heard throughout the city, AFP's correspondent in an eastern neighborhood said.

The violence rendered the rebel route out of the city -- via the southern district of Ramussa -- temporarily unusable, and trucks of food and other produce could not be brought into the city, the correspondent said.

Approximately 250,000 people live in the city's eastern districts, while another 1.2 million live in its western neighborhoods.

While rebel groups are accessing the city via Ramussa, the regime is using the Castello Road to the north of the city to reach areas it controls.

According to the Observatory, regime forces seized territory on the city's southern edges on Saturday.

"There are a lot of clashes and air strikes, and the regime made modest advances. They are trying to reinforce their positions," Observatory head Rami Abdel Rahman said.

The Observatory -- which relies on a network of sources inside Syria for its information -- says it determines what planes carried out raids according to their type, location, flight patterns and the munitions involved.

More than 290,000 people have been killed since Syria's conflict started in March 2011 and international efforts at putting an end to the war have faltered.