Updated

Crouching behind walls and firing from the corners of buildings, rebels are battling Syrian government troops in battered neighborhoods of Aleppo, the nation's largest city.

Guns raised, the fighters race through the rubble-strewn streets of the city's Moaskar Karmal Jabl sector, retreating behind sandbags as they take fire from better-armed regime troops. One young rebel fighter, a white scarf wrapped around his forehead, takes cover behind the bombed-out stone wall of a building.

The two sides have been fighting over Aleppo for weeks, engaging in street-by-street urban warfare with neither side able to score a decisive victory.

The Syrian military has used attack helicopters and warplanes to blast rebel positions. The rebels, with few heavy weapons and no aircraft in their arsenal, have been hitting back with assault rifles and machine guns.

The rebels claim to control half of Aleppo, a city that is key to control of the northern part of the country and its border with nearby Turkey.

Here's a gallery of photos from the fighting in Aleppo.