Heavy fighting took place in different sectors of the Syrian city of Aleppo on Sunday as opposition forces assaulted two regime strongholds in the city's northwest and south, a monitor of the war said.

Fighting for control of Aleppo, split between its regime-held west and opposition-held eastern neighborhoods, has intensified in recent weeks causing hundreds of deaths and depriving many civilians of power, water and vital supplies.

Fighters detonated car bombs before launching an attack on the Jamiat al-Zahraa district, an army base, the British-based Syrian Observatory for Human Rights said.

Opposition groups then attacked the regime army's positions in a cement factory on the city's southwest, adjacent to the mouth of a corridor into opposition-held east Aleppo that fighters had opened up a week ago, breaking a regime siege.

Earlier in the day, the Syrian regime army and its allies captured some buildings in the southwestern 1070 housing development, also located near the entrance to the opposition corridor into Aleppo.

Aleppo is one of the bastions of the rebellion to oust Bashar al-Assad, whose army is backed on the ground by Shi'ite militias from Iran and neighboring countries and from the skies by Russian air strikes.

PHOTO CAPTION

A man rebuilds a wall of a damaged building in the opposition held al-Katerji district in Aleppo, Syria August 13, 2016.

Reuters